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LIBRARY OF CONGRESS. 



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UNITED STATES OF AMERICA. 



Butler's Science Series. 



ELEMENTS 



OP 



CHEMISTET. 



if-^ 



BY ■ 



HENEY LEFFMANN, M.D., 



Lecturer on Toxicology at Jefferson Medical College; Demonstrator 

OF Chemistry at the Pennsylvania College of Dental Surgery; 

Member of the Society of Public Analysts of England. 




PHILADELPHIA: 
E. H. BUTLER & CO. 



\. 



Copyright 

By E. H. BUTJLER cS: CO., 
1882. 



^^^ (J. Westcott & Thomson, 

/''^X^ ty^ Stereotypers and Mectrotypers, Philada, 



PREFACE. 



The first fifty-two pages of the present work comprehend 
a concise summary of chemical principles arranged for pro- 
gressive study. The remainder of the work is an enu- 
meration of the principal facts of the science, sufficiently 
elaborate for those attending college lectures or pursuing 
the common-school course of study. The experience of a 
dozen years, during which I have instructed over two thou- 
sand pupils, has convinced me that the most satisfactory 
progress is attained by a preliminary instruction in the 
principles of the science before proceeding to its descrip- 
tive part. It is on this method that this work is arranged. 
Teachers, however, who prefer to begin at once with descrip- 
tive chemistry, and to introduce the discussion of chemical 
principles from time to time in the course, will find the 
subject-matter so classified and indexed as to allow such 
system to be followed without difficulty. 

The arrangement of the descriptions has been adopted 
as that best suited to render the acquirement of the facts 
easy, since bodies most alike in chemical relations are 
described in immediate succession. It has not been deemed 
necessary to follow the practice of the older manuals and 
defer the description of each compound body until all its 
elements have been described ; in this book important com- 



PREFACE. 



pounds have generally been presented in connection with 
their characteristic elements. 

The science of Chemistry has become very difficult in 
the last twenty-five years, not only from the immense num- 
ber of facts which have been presented, but also from the 
complexity of the theory, notation and nomenclature. That 
this manual may serve to lighten the labors of those who 
are endeavoring to acquire a knowledge of one of the most 
interesting and valuable of sciences, is the hope of 

The Author. 
715 Walnut Street, 

Philadelphia, Sept., 1882. 



CONTENTS. 



CHEMICAL PRINCIPLES. 

Introductory. 2. Notation. 3. Nomenclature. 4. Laws of Chem- 
ical Combination. 5. Atomicity. 6. Electrical Eelations of the 
Elements. 7. Eeactions. 8. Acids, Bases and Salts. 9. Quasi- 
elements or Radicles. 10. Combination by Volume. 11. Rela- 
tion between Specific Heat and Atomic Weight. 12. Numerical 
Eolations of the Atomic Weights. 



DESCEIPTIVE CHEMISTRY. 

INORGANIC. 

Classification. 

Chlorine Group : Chlorine, Bromine, Iodine, Fluorine, 

Potassium Group : Hydrogen, Potassium, Sodium, Lithium, Caesium, 

Rubidium, Silver. 
Oxygen Group : Oxygen, Sulphur, Selenium, Tellurium. 
Nitrogen Group : Boron, Nitrogen, Phosphorus, Arsenic, Antimony, 

Bismuth, Gold, Thallium, Vanadium. 
Carbon Group : Carbon, Silicon, Tin, Titanium, Tantalum, Niobium, 

Tungsten, Zirconium, Platinum, Palladium, Ruthenium. 
Calcium Ciroup : Calcium, Barium, Strontium, Lead. 
Copper (Jroup : Copper, Mercury. 
Zinc Group: Zinc, Magnesium, Cadmium, Beryllium, Thorium, 

Yttrium, Erbium. 
.1* .5 



CONTENTS. 



Iron Group : Aluminum, Iron, Manganese, Chromium, Nickel, Cobalt, 
Iridium, Ehodium ; Osmium, Molybdenum, Cerium, Lanthanum, 
Didymium, Indium, Gallium. 

OEGANIC. 

General Principles, Definitions of Terms, Changes of Organic Bodies, 
Nomenclature, Hydrocarbons and Derivatives, Alcohols and Ethers, 
Acids, Fats and Oils, Sugars and Starches, Glucosides, Fermenta- 
tion, Organic Acids, Cyanogen and Derivatives, Aijiines, Organic 
Bases. 



ELEMENTS OF CHEMISTRY, 



1. INTRODUCTORY. 

Chemistry is the science which investigates the composi- 
tion of bodies and the changes which occur in them under 
various influences. Of the many forms of change which 
occur in nature, Chemistry studies especially those which 
produce some alteration of composition, though of late years 
many actions have been noticed in w^hich the only change 
appears to be in the arrangement of the particles of the 
bodies, and many such changes are considered chemical 
phenomena. 

Material substances may exist in at least three forms — 
solid, liquid and gaseous. The passing of any body from 
one of these forms to the other is generally brought about 
by heating or cooling, and is called a physical, not a 
chemical, effect. In the same way, the condition called 
magnetism is not known to be attended by any alteration 
of composition. On the other hand, the rusting of iron, the 
combustion of coal, the decay of animals or plants, give rise 
to new substances, and are strictly within the province of 
chemistry. 

The material objects around us present much variety in 
color, form and general qualities. We can, by mechanical 
action, reduce most of them to fragments or even to fine 

7 



8 ELEMENTS OF CHEMISTRY, 

powder. Chemistry has taught us that many bodies are 
capable of another kind of division, which consists in sep- 
arating them into two or more substances unlike each other 
and unlike the original substance. This change is called 
DECOMPOSITION. A fragment of common salt, for instance, 
may be converted into a fine powder, but by other means 
it may be decomposed into two substances — one a brilliant 
solid, and the other a greenish-colored gas. These two 
substances seem to be incapable of further decomposition, 
and are called elements. Chemists, by experimenting 
upon a great number of bodies, have established the exist- 
ence of sixty-six elements, to each one of which a name has 
been given. A certain force, or form of energy, known as 
CHEMICAL AFFINITY, causcs thcsc elements to unite with one 
another and form compounds. Some of the elements occur 
in nature in the free or uncombined condition, but most of 
them are in combination; hence the various objects of chem- 
ical study are either elementary or compound. The elements 
are usually arranged in two groups or classes — metals and 
NON-METALS ; but such division is unsatisfactory. A better 
arrangement is into three groups — non-metals, metalloids 
and METALS. Even this, however, is not of much service, 
and will not be strictly adhered to in this work. The follow- 
ing arrangement into small groups is better for the purposes 
of study, and should be memorized sufficiently to enable the 
student to give without hesitation the members of the differ- 
ent groups, as this knowledge will be of great assistance in 
the study of the important compounds : 



Oxygen Group, 


Chlorine Group, 


Nitrogen Group. 


Carbon Group. 


Oxygen, 


Chlorine, 


Nitrogen, 


Carbon, 


Sulphur, 


Bromine, 


Phosphorus, 


Silicon, 


Selenium, 


Iodine, 


Boron, 


Tin, 


Tellurium. 


Fluorine. 


Arsenic, 
Antimony, 
Bismuth, 
Gold. 


Platinum. 



ELEMENTS OF CHEMISTRY. 



Potassium Gr 


•oup. 


Calcium Group. 


Zinc Group. 


Iron Group. 


Potassium, 




Calcium, 


Zinc, 


Iron, 


Sodium, 




Barium, 


Magnesium, 


Manganese, 


Lithium, 




Strontium, 


Cadmium. 


Aluminum, 


Hydrogen, 




Lead. 




Chromium, 


Silver. 




Copper 


• Group. 


!Nickel, 
Cobalt. 



Copper, 
Mercury. 

More complete lists are given in the latter part of the book. 

Atomic Theory. If we reduce a piece of sulphur or any 
other element to powder, it will be seen to be capable of be- 
ing further divided, and it would seem as if no limit existed 
to this division. Chemists, however, are now generally of 
the opinion that a limit does exist, and that every substance 
is made up of particles of definite size incapable of diminu- 
tion or destruction. These have never been demonstrated. 
The belief in their existence is dependent upon some difficult 
mathematical and physical considerations ; they are infinitely 
small, and equally hard, no matter what the nature of the mass 
which they make up. These particles are called atoms (a 
word derived from the Greek, and signifying indivisible), and 
any mass of elementary matter consists of a collection of a 
greater or less number of these atoms. It is now a generally 
accepted theory that even in elementary bodies the atoms are 
not perfectly free, but associated in pairs. A combination of 
atoms is called a molecule. When, therefore, we divide a 
piece of sulphur, we merely separate the molecules from each 
other. Sulphur is soft, carbon in the form of the diamond is 
very hard, but this difference in hardness between the two is 
due simply to the firmness with which the molecules of the 
two bodies hold together. Those of the diamond have a 
strong affinity, those of sulphur a weak affinity ; but in each 
body the molecules themselves are composed of atoms of 
infinite hardness. 

When a solid becomes a liquid or a liquid becomes a gas, 



10 ELEMENTS OF CHEMISTRY, 

or the reverse occurs, the molecules are not changed, but 
merely separated from one another. Hence the atoms in 
sulphur vapor are as hard and solid as those of solid sul- 
phur, but in the vapor the pairs or molecules which they 
form are separated by greater distances than in the case of 
the solid. The following will render this point clear: 

aa aa aa aa The element in the solid state, 

aa aa aa aa " " liquid " 

aa aa aa aa " " gaseous *' 

This does not represent the proportionate separation, but 
only the general idea that this change of state is a simple 
separation of molecules. According to this view, bodies in 
passing from solid to liquid, and from liquid to gas, should 
increase in volume, and in the reverse processes should de- 
crease ; and this we find to be the case with the vast majority 
of substances. 

The force which holds aiorm together and forms them 
into molecules is a chemical force, and is called chemical 
AFFINITY. Any number of molecules of the same kind may 
be held together in a mass : the force that does this is called 
COHESION. Molecules of diflferent kinds may also be held 
together ; such an efiect is called adhesion. 

Atomic Weights. Chemists have never been able to 
isolate or render visible atoms or molecules. Their size and 
weight remain entirely a matter of speculation and theory. 
Nevertheless, the progress of chemical research and the 
application of mathematics have developed some general 
principles. These are: 

1st. That the atoms of each element have a constant and 
definite weight. 

2d. That the atom of hydrogen is the lightest of all. 

3d. That combination takes place among atoms under the 
action of chemical affinity. 



ELEMENTS OF CHEMISTRY. 11 

Starting with the first two principles, numbers have been 
obtained which represent the weight of each atom compared 
to the atom of hydrogen. These numbers are called atomic 
AVEiGHTS. A complete list is given at the end of the book. 
It is not necessary for the student to commit them to 
memory. 



2. NOTATION. 



A CHEMICAL symbol is an abbreviation of the name of an 
element ; in most cases an initial letter is used, as C for carbon, 
P for phosphorus. As some elements have names beginning 
with the same letter, proper distinction is obtained by assign- 
ing the single letter to the most common, and attaching small 
letters to the other initials. Thus, C stands for carbon, Ca for 
Calcium, CI for chlorine, Cd for cadmium. Certain elements 
have difierent names in different languages, and for these the 
symbol is formed from the Latin name. Iron, for instance, is 
represented by Fe (ferrum) ; lead by Pb (pluvibum) ; silver 
by Ag (argentmii) ; potassium by K {kalium). 

Symbols are absolutely invariable. No symbol represents 
tw^o elements, no element has more than one symbol. The 
student should commit to memory thoroughly and accurately 
the symbols of all the important elements. A complete list 
of them will be found wdth the table of atomic weights. 

To express combination between elements — in other w^ords, 
to express the composition of a compound body or the mole- 
cules of an elementary body — the symbols are to be WTitten 
together like the letters of a w^ord. Such a collection of 
symbols is called a formula. 

The symbol, however, not only represents the element, but 
also one indivisible particle of it ; that is, one atom. Hence, 
the expression CaO not only shows a compound consisting of 
calcium and oxygen, but also indicates that it contains a single 



12 ELEMENTS OF CHEMISTRY. 

atom of each element. CaOa shows that two atoms of oxygen 
are present and one of calcium. In writmg these expressions 
certain rules are followed : 

1st. To multiply any single atom, a small number is at- 
tached to the lower right hand, as seen above, where O2 indi- 
cates two of oxygen. The formula C2H4O2 shows a combi- 
nation consisting of two atoms of carbon, four of hydrogen 
and two of oxygen. 

2d. To multiply several atoms by the same number, we put 
a large figure in front. Thus 2HC10 is equal to H2CI2O2 ; that 
is, the large figure multiplies the whole expression. This rule 
gives much trouble to beginners. 

3d. To multiply a portion of an expression, several methods 
are in use. We may enclose the part to be multiplied in 
parentheses, and attach the proper 'number to the lowxr 
right-hand corner. Ba(N03)2, for instance, equals BaNsOg ; 
C6H8(N02)205 equals C6H8(N204)05. The effect of the small 
figure is limited to the part within the parentheses. This 
method is especially adapted to multiplying symbols in the 
middle or at the end of a formula. To multiply the symbols 
at the beginning of a formula, we usually point off* or punc- 
tuate the part to be affected, and j)lace a large figure in front. 
Some irregularity prevails as to the particular sign used, the 
comma and semicolon both being em]3loyed. It is sufficient 
for the student to bear in mind that a punctuation-mark or 
plus-sign occurring in a formula will stop the multiplying 
effect of the large figure at the beginning of the expression. 
For instance, 2C2H5,H2N is equal to C4H10H2N ; similmiy, 
in 2FeS04 + HCl the letters following the plus-sign are not 
affected by the figure 2. If we wish to carry the multiplying 
effect to the end of the expression, we enclose it in paren- 
theses ; thus, 2(FeS04 + HCl). Here all the letters are equally 
influenced. 

Since the symbol of each element represents one atom, it 
follows that every symbol carries with it an idea of quantity. 



ELEMENTS OF CHEMISTRY. 13 

If we write HCl, the meaning is not merely that hydrogen 
and chlorine are in combination, but that the amounts by 
weight are in the proportion of the atomic weights ; i. e. \ 
(atomic weight H) to 35.4 (atomic weight CI). When the 
symbol is multiplied, the w^eight is also multiplied. For 
instance, H2O represents 2 parts by weight of H to 16 of O ; 
HgCL represents 100 parts of mercury and 70.8 (35.4 X 2) 
parts of chlorine. From these examples it appears that 
formulae give no exact idea of the percentage of the differ- 
ent elements unless we multiply each symbol by its atomic 
weight. The following illustration will perhaps make this 
point clearer : By burning sulphur in air or in oxygen we 
obtain a gas w^hich contains equal parts by w^eight of S and 
O. To use the formula SO would be incorrect, for the table 
of atomic weight shows that the atom of S equals 32, while 
that of O equals 16 ; SO, therefore, would show a relation 
of 32 to 16. The relation is 32 to 32 — that is, equal parts; 
hence, we must use the formula SO2, which gives us S = 32 ; 
02 = 32 (16 X 2), the proper pro^Dortion. In the same way 
we may reduce a more complicated formula. Potassium car- 
bonate is written K2CO3. Eeferring to the Table of Atomic 
Weights, we find the following numbers: 

K = 39, consequently K2 = 78 
C =- 12, " C = 12 

O = 16, " O3 = 48 

The sum of the atomic weights is called the molecular 
WEIGHT. In the example above given the sum is 148 ; we 
cannot reduce this sum in any way except by taking away 
one of the atoms ; for, by the atomic theory, we cannot 
remove a portion of an atom. To take aw^ay any atom is 
to change the composition of the body ; it is no longer potas- 
sium carbonate. Therefore, we say that the smallest portion 
of potassium carbonate that can exist will be 138 times as 
heavy as one atom of hydrogen. The same is true of the 
molecular weight of any body. It will represent the relation 
2 



14 ELEMENTS OF CHEMISTRY. 

between the weight of the smallest possible quantity of the 
body, its molecule, and one atom of hydrogen. With a 
number of compound gases it has been found that the molec- 
ular weight is equal to twice the specific gravity compared to 
hydrogen. The inferences from this fact will be discussed 
later. 



3. NOMENCLATURE. 

The names of chemical compounds are regulated by a sys- 
tem which depends essentially upon the employment of cer- 
tain terminations. 

In the old division of the elements into metals and non- 
metals the metals w^ere usually distinguished by the termina- 
tion "UM.'^ A change of this termination into "a" indi- 
cated combination with oxygen. Potassium (K) becomes by 
oxidation potassa (K2O) ; sodium (Na) becomes soda (NagO) ; 
magnesium (Mg) becomes magnesia (MgO). As the names 
of many of the common metals did not end in " um " unless 
the objectiouable Latin name was used, this rule was only of 
limited application. The tendency of the modern nomencla- 
ture is to make but little change in the names of the sub- 
stances called metals, and the terminations about to be pre- 
sented are not usually attached to bodies ending in ^' um,'' or 
to those which we commonly call metals, such as iron, silver 
and zinc. 

Chemical compounds which contain only two elements are 
called BINARY COMPOUNDS. They are usually named by 
joining the names of the elements present and attaching to 
one of them the termination " IDE." This termination may 
be conveniently regarded as an equivalent of the phrase 
" nothing else ;" that is, wherever it occurs it indicates that 
nothing else is present except what is expressly mentioned. 
Potassium iodide, for instance^ can contain nothing else but 



ELEMENTS OF CHEMISTRY. 15 

potassium and iodine ; copper sulphicZ^ can contain nothing 
but copper and sulphur. 

PbO Lead ox.ide. 

NaCl Sodium chloriV?<?. 

AgBr Silver bromic/e. 

The syllable " ide " is usually attached to the members of 
the oxygen, chlorine, nitrogen and carbon groups, and pref- 
erably to those of the first two groups. Thus, a compound 
of iron and carbon is called iron carbide, but a compound of 
carbon and chlorine is called carbon chloride. 

In many books, especially in older works, the word "of" 
will be found frequently used in the names of compounds. 
Instead of copper sulphide, we may see sulphide of copper, 
iodide of potassium for potassium iodide. This system was 
introduced into chemistry by an original mistranslation of 
French phrases in w^hich the word " de " occurred. Good 
usage has fortunately justified the entire omission of the word 
in English chemical nomenclature. 

As elements may combine in several proportions, forming 
several difierent compounds, this termination ide does not suf- 
fice for proper distinction, and chemists employ a system of 
prefixes used with this termination. These prefixes are 
formed mostly from the Greek or Latin numerals. The 
bodies CU2O and CuO are both properly called copper oxide, 
because they contain only copper and oxygen, but they are 
quite different substances. In the same w^ay, SO2 and SO3 are 
both sulphur oxides, but must be distinguished from each 
other. The distinction is made in this way : 

. Cu^O Copper si(6oxide. 

CuO " monoxide (also^roi^oxide). 

502 Sulphur Jioxide (also dent- or ^inoxide). 

503 " irioxide (also Peroxide). 

The terms in parentheses are now rarely used. In regard 
to the first prefix, suh, it is of rather uncertain meaning. It 



16 ELEMENTS OF CHEMISTRY. 

generally indicates deficiency ; that is, that the quantity of 
the element to which it is attached is less than it should be. 
We apply the term sub especially to compounds in which a 
member of the oxygen or chlorine group is deficient in 
amount. PbiCl, Zuslg, Cu^O are sub-compounds. 

With some of the elements, hoAvever, the normal proportion 
of combination is two of the first to one of the second, and 
here it has become universal custom to use the prefix mon. 
We have, therefore, 

K2O Potassium ??io?ioxide, 

NasO Sodium 7nonoxide, 

Ag20 Silver mo?ioxide, 

K2S Potassium ??io?iosulphide, 

and so on with all the series. The following includes the 
elements which show this exception: 

Chlorine, Hydrogen, 

Bromine, Potassium, 

Iodine, Sodium, 

Lithium, 

Silver. 

It is especially in the combinations of these bodies with 
members of the oxygen group that the irregularity is 
shown. 

Some elements form compounds in which the proportion is 
as 1 to I2, but as fractions are not allowed in formulae, the 
whole expression is multiplied by 2, which gives the propor- 
tion 2 to 3. FeOiJ becomes, therefore, Fe203. These are 
called ses^iu-compounds, and the above expression is iron 
sesquioxide. The word sesqui means one and a half, and 
conveys the idea that the relation between the two elements 
is as 1 to IJ (2 to 3). Higher proportions also occur. We 
have, for instance, 

CCI4 Carbon tetrachloride or quadrichloride. 

PCI5 Phosphorus pentachloride. 



ELEMENTS OF CHEMISTRY. 17 

In assigning names to compounds containing more than two 
elements, a great difficulty occurs from the very large num- 
ber of such compounds which may be formed. To express 
the names of all the elements would often make long words, 
so the general custom is either to leave solne elements unex- 
pressed or to give a name to a group of two or more of the 
elements. For instance, the substance KHO is called potas- 
sium hydrate. In this name only the K and H are men- 
tioned; the O is indicated by the termination. The com- 
pound KCN is called potassium cyanide, the combination CN 
being called cyanogen. This latter method of giving special 
names to groups is very common in organic chemistry. 

Among the most important of the compounds containing 
three elements are those which we call salts. This term 'is 
difficult to define ; it comes to us from the early days of chem- 
istry, when opinions as to the nature of substances were quite 
different from those held at present. Briefly, salts may be 
defined as substances formed by the action of acids upon cer- 
tain elements or their oxides. If we put zinc or zinc oxide 
into sulphuric acid, we get a zinc salt ; in this case zinc sul- 
phate. We can get salts also by direct union of many 
oxides ; for instance, when calcium oxide, CaO, acts upon 
carbon dioxide, CO2, we get calcium carbonate, CaCOs, which 
is a salt. 

Most salts contain three elements, of which oxygen is one, 
and the names are made by joining the names of the other 
two elements and addiug to them certain syllables which not 
only indicate the presence of oxygen, but also partly the 
amount. These syllables are " ate " and " ite." The former 
indicates the greater quantity of oxygen. Thus potassium 
sulphate and potassium sulphide both contain oxygen, but the 
former (sulphate) contains the more oxygen. Sodium nitrate 
and sodium nitrite contain the same elements, but their com- 
position is NalN'Os and ISTaNOa, respectively. 

It will aid in the comprehension of this subject if we extend 

2>^ 



18 ELEMENTS OF CHEMISTRY. 

the principle which has already been mentioned when speak- 
ing of the termination " ide." It was pointed out that this 
syllable could be regarded as equivalent to the phrase 
"nothing else/' In the same manner, the syllables "ate'' 
and " ITE " are to te regarded as meaning " something else/' 
and that something else is generally oxygen. With these 
points in mind the student will recognize, at a glance, that 
while in sodium sulph^<i6 but two elements are present, 
sodium sulphofie and sulphide will contain three. 

These two terminations are not sufficient to distinguish all 
the salts that may be formed from certain elements. For 
instance, potassium, chlorine and oxygen will unite in four 
different proportions, forming KCIO4, KCIO3, KCIO^, KCIO. 
In such cases the important or most common compound is 
distinguished by the termination "ate," and the one con- 
taining the next lower amount of oxygen by the termina- 
tion "iTE." 

The other compounds are indicated by the use of certain 
extra syllables, " hypo " and " hyper," the latter now gen- 
erally abbreviated to "per." The significance and use of 
these syllables are shown below : • 

KCIO4 Potassium perchlorate. 
KCIO3 " chlorate. 

KCIO2 " chlorite. 

KCIO " hypochlorite. 

From this table it is seen that " per " intensifies the meaning 
of any termination — that is, indicates more oxygen than if 
the termination were used alone ; while " hypo " diminishes 
the power of a termination — that is, indicates a smaller 
amount of oxygen than would be present if " hypo " were 
not used. Several other series of salts show the same prin- 
ciple, although not so perfectly as that above given: 

Na.^SO^ Sodium sulphate. 

Na^SOs " sulphite. 

NaaSOa " hyposulphite. 



ELEMENTS OF CHEMISTRY. 19 

When, in such compounds, hydrogen is present, we might 
use a similar system, but the custom of chemists has decreed 
that a different method shall be adopted. 

Taking the series of chlorine compounds given above, in 
place of the potassium salts we might have HCIO4, HCIO3, 
HCIO2, HCIO, and these might be called hydrogen per- 
chlorate, hydrogen chlorate, etc. ; such names are used by a 
few persons, but have not become current. The more fre- 
quent method is to drop the word " hydrogen," change the 
termination ate into ic, the termination ite into ous, and 
add the word acid. 

The series would therefore be, 

HCIO4 Perchlor2C acid. 

HCIO3 Chloric acid. 

HCIO2 Chlorous acid. 

HCIO Hypochloroi^s acid. 

Note particularly that the prefixes are retained without 
change, and that the syllable ic is found whenever, in the 
metallic salt, the termination was ate, and the syllable ous 
is found when the name has come from a compound ending 
in ITE. 

Under this rule we have the following transformations : 

Potassium sulphate | ^^,,, js to j ^i^lphuric acid 
K2SO4 3 ^ 1 H2SO, 

Potassium sulphite \ ^^ f Sulphurous acid 

K2SO3 J 1 H2SO3 

Potassium hyposulphite \ a f Hyposulphurous acid 

K2SO2 I 1 ^ li^SO^ 

Strictly speaking, no necessity exists for this variation. 
The compounds containing hydrogen ought to be regarded 
as salts. They exhibit, however, some incidental properties 
which distinguish them from the rest of the salts. They have 
a sour taste, redden vegetable blues, and have, as a rule, a 
wider range of chemical action. They stand out as a group. 



20 ELEMENTS OF CHEMISTRY, 

and from a very remote period have been called acids. The 
term is too well established in chemistry to be set aside. 

Sometimes we have bodies in which the hydrogen is only 
partly replaced by another element, and these are inter- 
mediate between the acids and the salts. Thus, KHSO4 is 
at once a potassium and a hydrogen compound. In such 
cases the name is a combination of both systems. The 
above compound, KHSO4, is called acid potassium sul- 
phate. Here the word acid calls attention to the existence 
of hydrogen, while the rest of the elements are indicated by 
the latter part of the expression. These acid salts are not 
unfrequently called &^-salts. Acid potassium sulphate, for 
instance, is generally known in commerce as potassium 
bisulphate; the corresponding acid carbonate, KHCO3, as 
bicarbonate. This use of the syllable bi is improper. If it 
means anything in this connection, it is that two molecules 
of acid are present, Avhich is not the case. In a few com- 
pounds of exceptional composition the title is used for want 
of a better one. K2Cr04Cr03, for instance, is called potas- 
sium bichromate. It is not properly so called; it does not 
contain two molecules of chromic acid, for CrOg is chromium 
teroxide ; but the more scientific title, anhydrochromate, will 
not be likely to find favor, and the incorrect name will long 
be used. 

The terminations " ous " and " ic " were formerly used only 
for acids or for the direct derivatives from them. Of late 
years these syllables have been much employed for distinc- 
tion in cases in which an element forms two sets of com- 
pounds. The following instances wdll explain this : 
Mercury forms two chlorides, two iodides, two sulphides, etc. 
The two series are distinguished as follows : 

Hg.Cl, HgJ, Hg,0 Hg,SO, 

HgCl, Hgl, HgO HgSO, 

The bodies in the upper row are called mercuro^is salts, those 
in the lower row mercuric salts. In the same wav we have 



ELEMENTS OF CHEMISTRY. 21 

FeO FeCl2 FeS04 Ferrous salts. 

FeA Fe,Cl6 Fe2(SO)3 Feme " 

Note particularly how these terminations are applied. They 
do not indicate the amount of the element to which they are 
attached, but of the other substance ; ous, as usual, means 
less than ic. 



4. LAWS OF CHEMICAL COMBINATION. 

Chemistry is an exact science ; that is, its laws and prin- 
ciples are mostly known and established. The great law of 
Chemistry is the law of constant proportion, and is 
expressed thus : Every chemical compound is definite in its 
nature, containing always the same ingredients and in the 
same proportions. 

It must not be supposed from this that elements can only 
combine in one proportion ; on the contrary, some of them, 
carbon and hydrogen for instance, combine in many propor- 
tions ; but the important point conveyed in the above rule is 
that each of these compounds is a different substance. As an 
excellent illustration of this the compounds of mercury and 
chlorine may be mentioned. If we unite 200 grains of mer- 
cury vrith 35.4 grains of chlorine, we get calomel ; if we unite 
200 grains of mercury with 70.8 grains of chlorine, we get 
corrosive sublimate. The two bodies are so different that if 
we did not know their composition we would suppose them to 
contain different elements. Calomel is insoluble in water, and 
non-poisonous. Corrosive sublimate is soluble in water, and 
one of the most violent of poisons. When we examine a great 
variety of chemical compounds, we notice that often when ele- 
ments combine in different proportions a simple arithmetical 
relation exists. A few cases will make this clear : 

The two compounds of oxygen and carbon are known, CO 
and CO2. Two compounds of sulphur and oxygen are known, 



22 ELEMENTS OF CHEMISTRY. 

SO2 and SO3. In the series of compounds of potassium, chlorine 
and oxygen, given a page or two back, we have 

KCIO 
KCIO2 
KCIO3 
KCIO4 

in which the proportion of oxygen is seen to increase regu- 
larly. The observation of many facts of this kind has given 
rise to a sort of principle in chemistry which is called the 
LAW OF MULTIPLE PROPORTION ; expressed thus : When two 
bodies comhine in more than one ^Dvojoortiony the higher propor- 
tions are multiples of the lower by a whole number. 

This law amounts to saying that if two elements are in 
combination in a low proportion, and we wish to add more 
of one of them, we must add one, two, three, four times, etc. 
as much. This principle, however, is not a law ; it is true of 
the simpler bodies only ; quite a number of elements combine 
in almost every proportion, and in many cases the multiple 
relation is only apparent, having been obtained by a sort of 
arithmetical trick. The great and important law of chemistry 
is that of constant proportion. 

The atomic weights express the proportion in which the 
elements combine. The atomic weight of hydrogen, for in- 
stance, is 1 ; that of bromine 80 ; and the only known com- 
pounds of these elements contain 80 parts of bromine to one 
part of hydrogen. 

In some elements the power of combination is such that 
more than one atomic weight of the one is required for one 
atomic weight of the other. Thus, the ratio of combination 
between H and O is II2O ; between N and H is H3N ; be- 
tween C and H is II4C. By substituting the atomic weights 
for the symbols we get the following proportions : 

H2= 2. H3= 3. H,= 4. 

O =16. N =14. C =12. 



H 


a 


4.7 


ii 


" N. 


H 


a 


3 


H 


" C. 



ELEMENTS OF CHEMISTRY. 23 

If we reduce the above ratios to the simplest form, we find that 
1 part by weight of H equals 8 parts of O. 

i (( Ci 

i iC ii 

These ratios are the simplest in which the elements can be 
compared, and are called equivalents, because they repre- 
sent the amount by vreight in which the elements are equal 
to each other. They were formerly much used in chemical 
calculation and arrangement, but the atomic weight is now 
preferred. The equivalent of any two elements in reference 
to hydrogen will also be their equivalent with reference to 
each other. Thus, in the above examples oxygen is seen to 
be equivalent to hydrogen in the proportion of 8 to 1. Sim- 
ilarly, carbon is seen to be equal to hydrogen in the propor- 
tion of 3 to 1. We find, further, that carbon is equivalent to 
oxygen in the proportion of 3 to 8, for the compound they 
form is CO2, in which, of course, C = 12 and O = 32, which 
is as 3 to 8. 

Compound bodies combine with each other in the propor- 
tion of their molecular weights. Lime (CaO) absorbs carbon 
dioxide (CO2), and forms calcium carbonate, CaCOa. The 
proportion by weight in which they combine is determined 
thus: 

Ca, atomic weight 40 C, atomic weight 12 

O, " " 16 O2, " " 32 

CaO, molecular weight 56 CO,, molecular weight 44 

The proportion is therefore 56 parts of CaO to 44 parts of 
CO,. 



5. ATOMICITY. 



It is mentioned above that elements may combine in several 
proportions, producing in each case distinct bodies. When 



24 ELEMENTS OF CHEMISTRY. 

compounds containing the same elements are compared, we 
generally find one proportion which seems to be the most 
natural one ; it is either most frequently or easily produced, 
or it is the one least liable to change. Hydrogen and oxygen 
combine in two proportions, thus : 

2 parts by weisrht H ) rr r\ tt ;^ • ^ 

_^ ^ ^ ^ ° ^r = ^2^ Hyaro2:en monoxide. 

16 " " " Oi ^ ^ 

^^^ ^ ^ ^ r =H202 Hydro2:en dioxide. 

These two bodies are very different. The first is water. It is 
formed whenever hydrogen is allowed to burn in air, and it is 
well known as a compound not liable to decompose. The 
second substance is very difficult to prepare and to preserve ; 
it is liable to explode. We can have no doubt, therefore, that 
the natural proportion of combination between H and O is 
H2O. Carbon forms with oxygen two well-marked com- 
pounds, CO and CO2. CO is formed w^hen carbon is burned 
in a deficient supply of air, but CO2 is formed when the 
carbon burns under natural conditions in a free draft of air 
or oxygen. CO, besides, shows a tendency to take up more 
oxygen, especially when heated, and it will combine with 
chlorine even at ordinary temperatures. CO2, on the other 
hand, shows no tendency whatever to combine with oxygen 
or chlorine. This list might be continued at great length, for 
all the elements have been more or less extensively examined 
with reference to this point. 

In developing this principle it has been found convenient 
to take the atom of hydrogen as a point of comparison, and 
to arrange each element according to the number of hydrogen 
atoms with which it forms the most permanent combination. 
Taking some important elements, for instance, we find their 
compounds with hydrogen as follows: 

CI combines with one H, forming HCl. 
Br " " " H, " HBr. 

O " " two H, " H2O. 



ELEMENTS OF CHEMISTRY. 25 

S combines with two H, forming HgS. 
N " " three H, " H3N. 

As " " " H, '' H3AS. 

C " '' foiuH, " HiC. 

These are not the only compounds that can be formed from 
these elements, but they are those which show only a slight 
tendency either to take new atoms or give up what they 
already possess. 

If an element does not form a compound with hydrogen, 
we may either combine it Avitli some other body, and then 
compare that to hydrogen, or we may displace hydrogen from 
the combination, and thus get an idea of the number of hydro- 
gen atoms to w^hich the element is equal. 

The greatest number of hydrogen atoms with which any 
element combines is called its atomicity, quantivalency, 
or YALENCY. Degrees of atomicity are indicated by names 
and signs ; the signs are the Roman numerals, the names are 
derived from the Greek or Latin names for these numerals. 
One degree of atomicity is indicated by the mark ('), and the 
body so marked is called a monad, or is said to be monatomic 
or monivalent. In the same manner, 

" indicates a dyad (diatomic or bivalent). 

"' " a triad (triatomic or trivalent). 

iv " a tetrad (tetratomic or quadrivalent). 

v " a pentad (pentatomic or pentivalent). 

vi " a hexad (hexatomic or hexivalent). 

The terms ending in " ad " are most convenient for use. 

Atomicity has nothing to do with the energy or activity of the 
element. It is a measure of cajjacity only. Bodies of high 
atomicity are often of weak affinity^ luhile some of the strongest 
chemical agents are of loiv atomicity. Chlorine has only one- 
third the atomicity of n itrogen, but it is many times more ener- 
getic as a chemical substance. 

Degrees of atomicity are determined by a study of the pro* 



26 ELJJMENTS OF CHEMISTRY. 

portions in which bodies combine ; hence a knowledge of the 
atomicity of the elements is a key to the composition of all 
their important and more j^ermanent compounds. The fol- 
lowing list should be thoroughly committed to memory, since 
it Avill enable the student to write correctly the formula of 
many common chemical substances : 

The chlorine and potassium groups are monad. 

The oxygen, calcium, zinc, copper and iron groups are 
dyad ; the iron group is often liexad. 

The nitrogen group is triad, and often pentad. 

The carbon group is tetrad. 

When elements are combined in such proportion that their 
atomicities are equal, the compounds are said to be satura- 
ted. This use of the word must be carefully distinguished 
from its older and more common use, meaning that a body 
has dissolved or absorbed as much of any substance as it can 
take up. In this sense we speak of saturated solutions, mean- 
ing solutions which contain as much of any substance as can 
be dissolved ; we speak also of gases being saturated with 
moisture, meaning that they contain as much moisture as 
can be held by them under the conditions. 

The above list can be used not only as a guide to the 
compounds which each element forms with hydrogen, but 
also as a guide to the compounds which the elements form 
with each other. The system is quite simple. Taking the 
monad group, for instance, it will be at once understood that 
as the members are all equal to one atom of H, they are 
equal to each other. Hence, K and CI will combine in equal 
atoms, forming KCl, potassium chloride. Similarly we will 
have NaBr, Agl, etc. The dyad elements have twice the 
combining capacity of monads ; we will find, therefore, that 
the compound of sodium and oxygen v>dll be Na^O. 

The general rule is that the elements unite in such propor- 
tions that the degrees of atomicities are equalized. Suppose 



ELEMENTS OE CHEMISTRY. 27 

we have a compound of CI and Sb ; Sb is a triad — that is, 
equal to three hydrogen atoms ; while CI is a monad, and 
equals only one hydrogen atom. It will therefore take 3C1 
to have the same capacity as one Sb, and the proper formula 
will be SbCla. If a compound of C and CI be desired, we 
fhid that as one is a tetrad and the other a monad, the re- 
sulting compound will be CCI4. 

The most difficult application of the rule is where triads 
and dyads are united, as in the compounds of oxygen and 
sulphur wdth nitrogen, phosphorus, arsenic and antimony. 
A few trials will show that to make the two atomicities equal 
we must multiply the dyad by 3 and the triad atom by 2. For 
example, SbaSs must be the formula of antimony sulphide, 
for 

S3 -.2X3 = 6 

A few^ formulae are here appended as additional illus- 
trations : 

Monad with monad H'Cr K'Cr Na'Br' 

" dyad W,0'' 

" triad H'sF'' Ag'sSb'^' 

" tetrad H^O^ 

Dyad " dyad Cu'^0'' Zn^'S'^ Fe^'O'' 

" triad P'^O'^s ^^''20^3 As'^S^ 

" tetrad O'0\ O'S'', 

It must, however, be borne in mind that compounds exist 
in which the proportion of the atoms difiers from what the 
rule requires ; but the essential character of such compounds 
is a tendency to change, either by taking new atoms or giving 
up some that they already possess. The normal compound of 
oxygen and carbon is, of course, CO2, in w^hich the one tetrad 
C atom is exactly saturated by the two atoms of dyad O. AVe 
are, however, acquainted wdth a well-defined body having the 
formula CO. This substance is rather a proof of the rule 



28 ELEMENTS OF CHEMISTRY, 

than an exception to it, for it shows a strong tendency to take 
up other atoms in order to complete its structure. Heated in 
the air, it combines with oxygen and forms CO2, and it unites 
with chlorine, forming a definite compound which will, of 
course, have the formula COCI2, since it requires two chlorine 
atoms to perform the function of one oxygen atom. 

So, also, the student must not fall into the error of suppos- 
ing that bodies in which the degrees of atomicity are equalized 
are necessarily without chemical activity. On the contrary, 
some of our most active chemical agents are saturated com- 
pounds. Hydrochloric acid, HCl, is an example of such a 
substance. It shows no tendency to take new atoms except 
under the condition that it at first give up a portion of its 
structure. It will dissolve potassium, for instance, but only 
by first losing its hydrogen, into the place of which the 
potassium enters. It will dissolve potassa (potassium oxide, 
K2O), but only by exchanging its hydrogen for the potassium. 
The changes may be represented as follows : 

K' + ffcr = K'cr + H' 

W,0" + 2H'Cr = 2K'Cr + H'^O^' 

This is, in fact, the nature of common chemical changes : they 
are substitutions of one element for another, the change always 
taking place in such a way that the element driven out is ex- 
actly equal in atomicity to the one that enters the combina- 
tion. If, instead of acting on hydrochloric acid with potassium, 
we use zinc, the quantity of HCl will have to be increased ; 
the reaction Zn + HCl cannot take place, since one atom of 
zinc must drive out two atoms of hydrogen, zinc being a dyad. 
Therefore, we say Zn -|- H2CI2 =^ ZnCla + H^, w^hich is in strict 
accordance with fact, as showing that one atom of zinc will 
set free twice as much hydrogen as one atom of potassium 
will. 

The degrees of atomicity given above are not invariable. 
The circumstances under which the variation takes place 
cannot be very w^ell defined; but the extent or rate of varia- 



ELEMENTS OF CHEMISTRY. 29 

tion is by a simple law, to which only a few exceptions need 
be made. When an element changes its atomicity, either in- 
creasing or diminishing, the change is by two degrees at a time. 
Elements of even atomicity remain even, passing, for instance, 
from hexads to tetrads, and finally to dyads, or vice versa; 
elements of uneven atomicity remain uneven, passing from 
pentads to triads and monads. 

Certain elements vary in atomicity in a way that appears 
to be exceptional, but in which we can, by a supposition, 
account for the change and yet preserve the application of 
the law. These bodies are supposed to have the property 
of combining with themselves in such a manner as to form 
double atoms, possessing an atomicity greater than either 
atom singly, but less than the sum of the atomicities of the 
two atoms. For instance, iron, which is generally a dyad, 
becomes in certain compounds a tetrad, but instead of form- 
ing compounds upon this basis, two atoms of iron unite and 
form a double atom or molecule, w^hich then forms compounds 
with other elements. A short reflection will show that this 
molecule, formed from two atoms each having a capacity of 
four, will have a power of six, one degree of atomicity in each 
atom having been consumed in forming the compound. 

For all cases of varying atomicity, whether regular or 
irregular, the terminations ous and ic are much employed, 
ous indicating the lower degree and ic the higher. We have 
in this way mercurous (lower atomicity) and mercuric (higher 
atomicity) salts, ferrous (dyad) and ferric (hexad) compounds. 
Indeed, in the use of the termination of the acids the same 
principle is carried out, sulphurous acid being the compound 
in which sulphur has a low^er (tetrad) atomicity ; sulphuric 
acid one in which sulphur has a higher (hexad) power. 

In arranging formulae containing three elements the appli- 
cation of the law of atomicity becomes somewhat difficult. 
In many common cases it will be found that the atomicity 
of one of the elements is much higher than it is in bodies 
3* 



30* ELEMENTS OF CHEMISTRY. 

containing two elements ; sulphur, for instance, is a dyad in 
binary compounds, but in the sulphites and sulphates it is, 
respectively, a tetrad and hexad. When oxygen is one of 
the three elements, we usually count it against the sum of the 
other two. Taking an instance of the salts above mentioned, 
we would get the following formulae : 

Potassium sulphite K'^S^'O^s 

Copper sulphate Cu^'S'^O'^^ 

In each case the atomicity of the oxygen is equal to the sum 
of that of the other two elements. 

For the student, however, the safest and shortest rule wdll 
be to commit to memory, thoroughly, some standard formulae 
containing three elements, and from these, by very simple 
rules, a large number of compounds can be built up. 

These formulae are — 

H2SO4 Sulphuric acid. 

H2SO3 Sulphurous acid. 

H2CO3 Carbonic acid. 

HNO3 Nitric acid. 

HNO2 Nitrous acid. 

HCIO3 Chloric acid. 

H3PO4 Phosphoric acid. 

The derivatives from these bodies form a large part of 
common chemical substances. If we wish to write the 
formula of any metallic salt, we substitute the proper 
amount of metal for the hydrogen in the corresponding 
acid. Let it be required to write the formula of potassium 
carbonate ; the reasoning would be as follows : Carbonic acid 
is II2CO3, potassium is a monad ; two atoms of potassium will 
be required to substitute the two atoms of hydrogen, and the 
formula is K2CO3. By the same reasoning copper sulphate 
may be deduced. Sulphuric acid is II2SO4, copper is a dyad ; 
one atom of copper w^ill displace tw^o of hydrogen ; therefore, 
CUSO4. When the standard formula contains too small an 



ELEMENTS OF CHEMISTEY, 31 

amount of hydrogen, we must multiply the expression by 
some whole number. For instance, the formula of copper 
nitrate will be deduced in this manner ; Nitric acid is HNO3 
copper is a dyad ; copper will therefore replace the hydrogen 
of two molecules of nitric acid ; hence, Cu(lsr03)2 or CUN2O6. 

Whenever we take one or more atoms from a saturated 
compound, we leave the compound unsaturated to a degree 
equal to the number of hydrogen atoms to which the removed 
atoms correspond. The molecule H^C is saturated. The mole- 
cule H3C is obtained by removing H, and is therefore a monad ; 
H2G is obtained by subtracting a second H, and is therefore 
a dyad ; and so on. The atomicity of any molecule can thus 
be obtained by finding how much hydrogen is required to 
form a saturated compound. By this method we determine 
that HO is a monad, for it requires but one atom of H to 
complete the molecule ; CO3 is a dyad, for it requires H2 
to form the saturated compound H2GO3 ; PO^ is a triad, for 
it forms H3PO,. 

Graphic Formulae. A convenient and much-used method 
of indicating atomicities is by graphic formula. These 
consist of the symbol of each element, with bonds or prolon- 
gations the same in number as the degrees of atomicity. Tak- 
ing some common elements as examples, we have 

monad dyad triad tetrad pentad 

K— — O— — P— — C— =N= 

I 
These bonds may be attached in any position or direction as 
long as the proper number is used. Carbon, for instance, 
may be written as above, or 

or in any other w^ay, provided four bonds are present. 

The practical application of this graphic notation to the 
writing of chemical formulae is easy. We link together the 
bonds of the different elements, and when all the points are 



32 ■ ELEMENTS OF CHEMISTRY. 

joined the compound is complete and is a saturated molecule. 
Two bonds of one atom, however, can never be attached to a 
single bond of another atom. We cannot have K — =0, but 
K — O — K, showing us that the composition of potassium mon- 
oxide must be K2O. The follov/ing are examples of some 
common compounds written graphically : 

H— CI ; H— O— H ; H— N~g ; 

0=C=0. 

AVe may also indicate unsaturated molecules. Thus, - 

0=C= shows that carbon monoxide is a body having 

CI 
two degrees of atomicity unsatisfied ; 0=C=pi that two 

atoms of chlorine have combined and satisfied this free 
atomicity. 

The only objection, perhaps, to the use of graphic formulae 
is the danger that the student may think that the atoms 
actually have spokes or projections on them, or are arranged 
in the somewhat . architectural manner shown in the formulae. 
K — O — H does not mean that in potassium hydrate the atom 
of O is flanked on either side by a potassium and by a hydro- 
gen atom, or that the atoms are connected by hooks or prongs, 
but merely that the oxygen atom has certain degrees of affinity 
which are satisfied by other atoms. 

A special application of this notation is to explain the 
nature of those changes in atomicity which have already 
been mentioned. The atom of sulphur, for instance, is in 
some combinations a hexad, in others a tetrad, in others a 
dyad. This progressive diminution of capacity may be sup- 
posed to arise from the bonds of affinity combining with each 
other in pairs ; thus : 

Hexad S Tetrad S Dyad S 

^s-- =s-- cs== 

The same principle can be shown with an element of uneven 
atomicity : 



ELEMENTS OF CHEMISTRY. 33 

Pentad N Triad N Monad N 

I I 

. . I I 

Since such combinations cannot take place unless both 

points are saturated or neutralized, the decrease of atomicity 
must take place by two degrees. 

The nature of the change by which the iron atom passes 
from a dyad to a hex ad condition can be very well show^n by 
this method. Dyad iron, graphically represented, w^ould be 
( Fe=, in which two bonds have satisfied each other, leaving 
two still active. In the higher degree of atomicity the con- 

! I 

dition is — Fe — Fe — , one bond of each atom havina: com- 

I I 

bined and linking the two in chemical union. Ferric oxide 
and ferric chloride would be 

O O CI CI 

II II II 

Fe Fe CI— Fe— Fe— CI 

— O— CI CI 



6. ELECTRICAL RELATIONS OF THE 
ELEMENTS. 

Electrical excitement exhibits two opposite conditions, 
called respectively positive and negative. These condi- 
tions are produced in any apparatus developing electricity. 
The points at which the electrical excitement is manifested — 
for instance, the wires of a battery — are called the poles. 
The positive pole is usually distinguished by the sign -f , and 
the negative by the sign — . 

These have a strong tendency to unite and neutralize each 
other. On the other hand, positive electricity repels positive, 
and negative repels negative. Two bodies charged with dif- 



ELEMENTS OF CHEMISTRY, 



fereiit kinds of electricity will attract each other, but if 
charged with the same kind of electricity wdll repel. The 
law is generally expressed as folloTys: Like electricities repel; 
unlike^ attract. 

These principles have been applied to the determination of 
some important relations between elements. A current of 
electricity decomposes a large number of compound bodies, 
and some elements appear at the positive pole, and others at 
the negative. Thus, potassium will be liberated in contact 
w^ith the surface negatively charged, and oxygen in contact 
with the positive surface. This will be the invariable result 
with these elements, no matter what compounds be taken for 
the experiment, but with many other elements the effect wdll 
depend upon the nature of the compound. With H2S the 
suljohur will appear at the positive pole ; with SO2, at the 
negative. This difference is due to the superior attraction of 
oxygen to the positive pole; it seems to compel the sulphur 
to go to the other point. 

Since unlike electricities attract, it follow^s that elements 
which go to the positive side must be negative, and those at 
the negative side must be positive. Very frequently w^e use 
the term " electro " in this connection ; thus we say, zinc 
is electro-jjositive ; chlorine is electro-negative, 

A body is not absolutely positive or absolutely negative, 
but is simply more positive or more negative than some other 
substance. Nevertheless, as the list of elements is limited, we 
will have two bodies wiiich, by their high affinities, will stand 
at the extremes of the scale, one being ahvays negative, the 
other always positive. Leaving out of consideration some 
rare elements, we may place potassium as the most positive, 
oxygen as the most negative. 

The follow ing table shows the common elements arranged 
in the order of their electrical relations : 
K, Na, Mg, Zn, Fe, Pb, Cu, Ag, Hg, H, C, P, S, I, Br, CI, O. 
Each element of this list will be positive when in combina- 



ELEMENTS OF CHEMISTRY. 35 

tioii with any element to tlie riglit of it, negative Avhen in 
combination with any to the left. 

These principles have an important application in deter- 
mining chemical changes. The greatest chemical attraction 
generally exists between elements most widely separated in 
their electrical relations. We may, by this means, often dis- 
cover the most probable result of any chemical action, as is ' 
shown in the next section. 



7. REACTIONS. 

Chemical symbols are employed not only to show the 
composition of bodies, but also to show exactly the nature 
of the chemical changes w^hich occur w^hen different bodies 
are brought in contact. When so used the expression is 
called a reaction. Certain compounds, which are much 
used for producing reactions, are called reagents, though 
strictly all the substances present take equal part in a reac- 
tion. When we pour vinegar upon a marble slab, w^e say, 
in ordinary phrase, that the marble is corroded, but, in fact, 
the vinegar is equally acted upon ; both substances are 
changed in composition, both are rendered unfit for their 
original uses ; in other words, they have not only acted ; they 
have reacted, and are therefore both reagents. 

A reaction is substantially an expression of the results of 
an experiment, and, when correctly written, gives us the 
proportion in Avhich bodies are to be used and the propor- 
tion of the resulting substances. We can never be abso- 
lutely sure of the correctness of any reaction until we make 
the experiment and analyze the result ; but the progress of 
Chemistry has made known certain laws of change which 
enable us to predict, or infer, many results w^itliout the 
necessity of actual observation. Every noAV and then, how^- 



36 ELEMENTS OF CHEMISTRY. 

ever, the analogy fails, and experiment disappoints the sug- 
gestions of theory. 

Reactions are written by placing in proper proportion, 
connected by + signs, the formulse of the bodies concerned, 
then writing the sign =, and following this by the formulae 
of the resulting bodies. For instance, 

AgNOs + HCl = AgCl + HNO3 

expresses that on bringing together silver nitrate and hydro- 
chloric acid a chemical change occurs by which silver chloride 
and nitric acid are produced. The principal difficulties in 
regard to reactions are: 1st. To know whether a given 
change will take place ; 2d. To know the quantities of the 
bodies to be used ; 3d. To know the nature of the resulting 
bodies. These points may be taken up in order. 

1st. In the simplest cases the nature of the reaction will be 
determined by the affinities of the elements as governed by 
their electrical relations, the change taking place in such a 
w^ay that the element having the stronger electric affinity will 
drive out and supplant the element of similar but w^eaker 
affinity. A reference to the table of electrical affinities 
will show that chlorine is more strongly negative than bro- 
mine, and bromine than iodine. Accordingly, we find that 
when chlorine acts upon the bromides they are decomposed, 
the bromine being expelled, and that bromine, in turn, expels 
iodine from combination. Therefore, such reactions as 

KBr + Cl==KCl + Br 
KI + Br = KBr + I 

are simply illustrations of the general electrical relations of 
elements concerned. If these affinities were the only active 
causes of chemical change, the subject would be quite simple, 
but by repeated experiment chemists now know that the sur- 
rounding circumstances may suspend or modify the play of 
affinities, so as to produce an endless variety of chemical 
action. It is hardly necessary to remark that all the modi- 



ELEMENTS OF CHEMISTRY. 37 

fying influences are not yet known, but a few of the more 
important will be considered. 

Chemical action is greatly aided by reducing the substances 
to powder or to the liquid form. By such means we expose 
more surface for action, and we also secure more intimate 
mixture of the reactive bodies. Iron in the form of wire 
can be burned only with difficulty ; in the form of filings 
it burns with some ease ; in the very fine condition known 
as reduced iron (q. v.) it can be lighted with a match ; and 
by heating the oxalate it can be obtained in so fine a form as 
to take fire on exposure to the air. This progressive increase 
of afiSnity is due to progressive fineness of division. 

A mixture of sodium carbonate and tartaric acid will not 
be changed by very intimate mixture in fine powder, but as 
soon as thrown into water the copious escape of gas will show 
that the solution has brought the atoms within sufficient range. 
A large number of operations in assaying and metal- working 
are dependent upon the effects of melting in causing chemical 
action. 

The physical forces, light, heat, electricity, etc., are fre- 
quent causes of both combination and decomposition. The 
respiration of plants, the fading of colors, the methods of 
photography, are familiar instances of the action of light. 
Heat is one of the most frequent agents, and electricity has 
been pointed out in a previous section as not only a cause of 
decomposition, but also as a means of determining the relation 
of the different elements. Besides the direct conditions which 
modify chemical action and disturb the simpler relations of 
affinity, a few influences exist which are dependent partly 
upon incidental circumstances and partly upon the nature of 
the compounds that are to be formed. These will be briefly 
enumerated : 

(a) Nascent State. Nascent means *'born," "brought 
forth," and expresses, when applied to an element, the fact 

4 



38 ELEMENTS OF CHEMISTRY. 

that it has just been set free. In such a condition its 
affinity may be very much higher than ordinarily. Arsenic, 
for instance, does not combine with hydrogen when the two 
are brought together from different yessels, but if we arrange 
the apparatus so that the hydrogen is set free — that is, becomes 
''nascent'* — in presence of the arsenic, a compound, AsHs, is 
formed rapidly. Very extended use is made of this influence 
of the nascent state in forming compounds. 

(6) Insolubility. When in any liquid we bring together 
substances wdiich are ca23able of forming a body insoluble in 
the liquid, that insoluble compound will be j^roduced in spite 
of the general relations of affinities. This influence of insol- 
ubility is the basis of a large number of tests and other chem- 
ical operations. 

When the formation of the insoluble compound w^ould re- 
quire a powerful chemical agent to be set free, the change 
will not take place unless, of course, the added substance is 
stronger than the one to be liberated. Carbonic acid forms 
with calcium a body Cjuite insoluble in water, but this body 
cannot be formed by passing carbonic acid into calcium sul- 
phate. The reason is shown at once on examining the con- 
ditions of the experiment. The reaction would haye to be 
CaS04+H2C03 = CaC03 (insoluble) + H2SO, ; that is, sul- 
phuric acid Avould be set free. The affinity of H.COs i"?, 
under ordinary conditions, so much below that of H2SO4 
that the former will not driye out the latter. The condition 
becomes changed if we assist the action of the carbonic acid 
by some substance which has an affinity for sulphuric acid 
and will preyent its being set free. CaSO^ + Is'a2C03 will 
produce immediate action, resulting in CaCOs + Na2S04. 
This reaction illustrates a common method of keeping the 
powerful affinities in abeyance, and thus allowing secondary 
influences full play. Some of the arsenic tests show the 
principle strikingly. Arsenous acid added to CuSO^ pro- 
duces no action, because the affinity of the SO4 is too strong, 



ELEMENTS OF CHEMISTRY, 3D 

but by adding a little ammonia the strong affinity this has for 
SO4 assists in breaking up the copper sulphate, and imme- 
diately a precipitate of copper arsenite falls. 

(c) Volatility. This is the second influence that disturbs 
ordinary affinities. If a body is capable of being converted 
into a gas, this fact will diminish its chemical power ; fixed 
substances that have ordinarily less affinity will drive it out 
of combination. Boric acid, for instance, is one of th^ weak 
acids, yet at a red heat it will drive out even sulphuric acid. 
The cause is, in the main, that at this temperature sulphuric 
acid is volatile, while boric acid is fixed. Chemists make, as 
is well known, much use of the action of heat as a modifier 
of chemical action, and frequently it is this influence of vola- 
tility which is brought into play. 

The ease with which hydrogen is driven out of combination 
may be regarded as due to its volatility, it being a gas even 
at low temperatures. 

yd) Mass. Sometimes chemical action seems to be governed 
by the c^uantity of the substance present. If we pass water 
vapor over red-hot iron, iron oxide is formed and hydrogen 
is set free ; if we pass the hydrogen back over the iron oxide, 
steam is formed and iron set free. In the first case the water 
is in excess and exerts an oxidizing influence ; in the second, 
the hydrogen is in excess and exerts a deoxidizing influence. 
The effect of mass is indefinite and uncertain, and need not 
enter into the ordinary working of reactions. 

It will seen to be a deduction from these statements that 
no substance can be set down as absolutely the strongest in 
affinity. It cannot be determined what is the strongest acid 
or the strongest alkali, except under specified conditions. 

2d. The proportion in which bodies react is usually strictly 
according to their atomicities. Let it be required to write 
the reaction between mercuric chloride and potassium iodide. 
The formulae are HgClj and KI, but the bodies will not react 



40 ELEMENTS OF CHEMISTRY. 

in this proportion, for the Hg will require I2, and CI2 will require 
K2. The proper reaction is HgCl^ + 2KI == Hgl^ + 2KC1. 
In the same way, antimony sulphide and hydrochloric acid 
can only act upon each other in the ratio SbjSg + 6HC1, be- 
cause, Sb being a triad, Sba will combine with Clg, and S being 
a dyad, S3 will require Hg. 

3d. If a chemical change occurs when two given substances 
are brought in contact, its nature will depend principally 
upon the electrical relations of the elements concerned. In 
the reaction HgCla + H2S the only possible result is the com- 
bination of S with Hg and H wdth CI, as is shown at once by 

placing the proper signs over the elements, Hg CI2 + H2 S. 

+ + — 

Such a combination as Hg H2 or CI2 S could not take place, 
since it requires like electricities to attract, which is against 
the rule. In beginning with reactions, the student will do 
well to place the proper signs over each element, and these 
signs will be a useful guide and control. When substances 
containing three elements are part of the reaction, the signs 
may be placed thus : 

+ - +- +- +- 

Ba(:N'03)2 + K2SO4 = BaSO, + 2KNO3. 

The placing of the single sign over the two elements is 
simply an evidence of the fact that in ordinary reactions 
these act as a single element. 

The following formulae will further illustrate the general 
principle : 

+- +-+-+- 

Ag NO3 + Na CI = Ag CI + Na NO, 

+ - + +- + 
H, O + K, = K, O + Hj 

+— - + - — 
H^O + Cl^^H^Cl.+ O 

+ — ++- +— +- +- 
Ba CI, + K H SO, = Ba SO, + K CI + H CI 



ELEMENTS OF CHEMISTRY. 41 

In the last reaction the electro-positives K and H may seem 
to be in union, but this is not the case. Each is independently 
united to the SO4, which is a dyad. The formula might be 

+ — 
written tt SO^ 

In writing reactions in which any element in the free state 
is expressed, it is now customary to use such proportions as 
will give an even number of atoms of the element. Thus, in 
giving the reaction of sodium upon hydrochloric acid, it would 
be written 

Na^ + 2HC1 -= 2NaCl + H^, 
and not 

Na + HCl^NaCl + H. 

This system has been adopted in deference to the theory 
that no atom exists alone, but that even elementary bodies 
have their atoms united in pairs. No advantage of any 
practical character accrues to the student from this com- 
plication ; and if the reaction is known and understood in 
the simpler form, an easy multiplication will change it into 
the other. 



8. ACIDS, BASES AND SALTS. 

These terms, introduced in the earlier days of chemical 
science, when the composition of bodies was but imperfectly 
understood, are still retained, but with very vague and un- 
certain meaning. The old definition of an acid was a body 
having a sour .taste, a power to afifect vegetable colors, espe- 
cially to turn blue colors red, and forming definite compounds 
called salts, Lavoisier had advanced the doctrine that all 
acids contained oxygen, but the existence of sulphur acids 
and the acids of the chlorine group upsets this view. The 
study of the anhydrides, or, as they were first called, anhy- 
drous acids, showed that water was necessary to the acid 
4 * 



42 ELEMENTS OF CHEMISTRY. 

condition, and thus was brought about the present view that 
hydrogen is the essential element of an acid. The explana- 
tion of these relations is given elsewhere. 

Bases were defined to be oxygen compounds, capable of 
uniting with an acid and neutralizing it. This definition 
was subsequently modified by including sulphur, selenium 
and tellurium as capable of forming bases. 

Salts were defined as bodies formed by the action of an 
acid upon a base. The reactions 

CaO + H,S04 = CaSO, + H^O, 
CaO + 2HC1 = CaCl^ + H^O, 

are instances of such effects. The above definition, however, 
does not include the production of a salt by direct action of 
a halogen, or of an acid, upon a metal ; thus : 

Zn + H,SO, = ZnSO, + H^ 
Zn + Cl2 = ZnCl2. 

Intimately connected with this subject is the meaning of 
the terms acid, alkaline and neutral, as applied to the 
conditions of substances. If we add a drop of sulphuric 
acid to a solution of the coloring matter of purple cabbage, 
the color will change to red ; by the addition of a small 
amount of soda the color will be restored, and by further 
addition will* be changed to green. The soda is a base ; it 
has combined with the acid and deprived it of its chemical 
activity. By this combination the soda has also been neu- 
tralized, and it is only by adding it in excess, that we can 
get its specific action on the color. Other coloring principles 
show similar effects. 

Litmus is a red color that becomes blue on the addition of 
a base, and of course has the red color restored on the addi- 
tion of an acid. It is usually sold in the blue condition, and 
is used either in solution in Avater or in the form of litmus- 
paper — strips of paper soaked in the solution and dried. 



ELEMENTS OF CHEMISTRY. 43 

Cochineal is much used as a substitute for litmus; acids 
turn it orange-yellow, and bases turn it purplish. 

It would seem that by the use of these tests we could de- 
termine whether a substance was an acid, a base or a salt, 
but, unfortunately, the reactions just given apply only to 
cases in which acids and bases of similar intensity are com- 
bined. When soda, which is a strong base, is united to sul- 
phuric acid, which is a strong acid, the compound is neutral ; 
but the union of soda with a feeble acid like boric produces 
a salt which is alkaline ; and the union of copper oxide with 
sulphuric acid gives a body which is acid to the tests men- 
tioned above. These color reactions are of some importance 
in practical chemical operations, but they have no value in 
determining the theoretical relations between acids, bases 
and salts. 

Salts may be divided into four classes : 

Normal salts, in which the hydrogen of the acid is re- 
placed by a single element, combined according to its atom- 
icities. The acids themselves are normal salts : 

H2SO4 Hydrogen sulphate (sulphuric acid). 

NasCSs Sodium sulpho-carbonate. 

KNO3 Potassium nitrate. 

Mixed salts, in which two or more elements have re- 
placed the hydrogen. When some hydrogen remains, the 
body is usually called an acid salt : 

HKCO3 Acid potassium carbonate. 

KNaCiH^Oe Sodio-potassium tartrate. 

It must be noticed that KaCrO^ is not a mixed salt; the 
chromium has not replaced any of the hydrogen of the 
acid. 

Double salts, in which two complete salts of either of the 
above classes unite to form a definite compound which is gen- 
erally distinctly crystalline : 



44 ELEMEJSTS OF CHEMISTRY, 

K2SO4 + Al2(S04)3 Potassium and aluminum sulphate. 
BaCOs + CaCOs Barium and calcium carbonate. 
2KC1 + PtCli Potassium and platinum chloride. 

Conjugated salts, in which a definite salt is united with 
a body not a salt. A great variety of these is known, and 
many are of uncertain composition. Two important classes 
may be recognized: 

(a) Oxy-salts, called frequently basic or sw6-salts, in which 
a basic oxide is united with the salt, thus : 

Bi(N'03)3 + BigOs Bismuth oxynitrate. 

SbCls -|- SbaOs Antimony oxychloride. 

(6) Anhydro-salts, called frequently acid or 6i-salts, in 
which an anhydride is united with the salt, thus: 

K2Cr04Cr03 Potassium anhydrochromate. 

2NaB02 + B2O3 Sodium anhydroborate. 

Salts formed by one atom of a monad are called mono- 
basic ; by two atoms of a monad, dibasic ; by three atoms, 
TRiBASic; by four, tetrabasic, thus: 

Metaphosphoric acid HPO3 is monobasic. 
Sulphuric acid H2SO4 is dibasic. 

Sodium sulphantimonate NaaSbSi is tribasic. 
Potassium silicate K4Si04 is tetrabasic. 



9. QUASI-ELEMENTS, OR RADICLES. 

Quasi is a Latin word meaning "as if.'^ Quasi -ele- 
ments are molecules which have the power of forming com- 
pounds "as if" they were elements. They are also called 
RADICLES (often incorrectly spelled radicals), because they 
may be looked upon as the root or basis of the compounds 
into which they enter. Practically, any unsaturated mole- 



ELEMENTS OF CHEMISTRY. 45 

cule may be regarded as a radicle. Some of the important 
ones to which special names have been given are — 

CN, cyanogen, electro-negative monad, resembling the 

chlorine group. 
HO, hydroxyl, a monad combining with both negative 

and positive bodies. 
H4N, ammonium, electro-positive monad, related to the 

potassium group. 

By deducting tlie hydrogen from acids we get their radicles. 
Thus : 

The radicle of H^SO^ is SO4. 
" HNO3 is NO3. 

As acids are saturated molecules, the atomicity of such 
radicles will be equal to the number of hydrogen atoms 
which have been taken away. 

NO3 is therefore a monad radicle, 
SO4 " dyad 

PO4 " triad 

SiO^ " tetrad " 

because the respective acids are 

HNO3, H,S04, H3PO,, H.SiO^. 

Organic chemistry presents us with a large number of 
radicles, the majority of which contain carbon and hydro- 
gen. 



10. COMBINATION BY VOLUME. 

In the section on the laws of chemical combination men- 
tion was made of the fact that the elements combined wdth 
each other in definite proportions, generally in the proportion 
of the atomic w^eights or some multiple of them. Modern 
chemical research has called attention to important facts in 



46 ELEMENTS OF CHEMISTRY. 

regard to the proportion by volume or hulk in which the com- 
bination takes place. As yet, no very exact or important 
results have been obtained from the study of the volume in 
the solid or liquid form, but in the state of gas or vapor the 
relations of the different elements are quite striking. 

If we weigh equal volumes of the elements in the state of 
gas, we find that their relative weights will, with a few excep- 
tions, be in exact proportion to their atomic vreights. For 
instance, a vessel which holds 1 grain of hydrogen (about 47 
cubic inches) will hold the follow^ing quantities of other ele- 
ments, it being understood that all the bodies are in the state 
of gas and at the same temperature and pressure : 



ement. 


Atomic Wei 


gilt. 


Wt. of vol. 


, equal to 1 vol. of H. 





16 






16 


s 


32 






32 


01 


35.4 






35.4 


I 


127 






127 


Br 


80 






80 



Some of the elements cannot be converted into vapor, and 
consequently cannot be compared on this system. Among 
these are carbon, silicon and many of the common metals. 
These practically resist the action of the highest temperature 
which can be used in such experiments. A few elements 
show results wdiich are exceptional ; among these are — 

Element. Atomic Weiglit. Wt. of vol., equal to 1 vol. of H. 

As 75 150 

P 31 62 

Hg 200 100 

In the case of phosphorus and arsenic the weight is twice 
as great as what analogy w^ould require ; in the case of mer- 
cury, half as great. 

Changes in temperature and pressure produce changes in 
the volume of gases, and all gases are affected nearly equally. 
It is pointed out elsewhere that a change of volume is due 



ELEMENTS OF CHEMISTRY, 47 

to a separation of the molecules or atoms, and not to any 
change in the volume of the atoms themselves. It is a rea- 
sonable assumption that if t^vo gases expand equally under 
the same conditions, it is because they contain the same num- 
ber of interspaces in Avhich the expansion takes place. Hence 
a law, which is expressed thus : 

Equal volumes of elementary gases contain equal numbers of 
molecules. 

The weight of the atoms of each element may be deter- 
mined by this law^ If a given volume of hydrogen contains, 
say, 1000 molecules, the same volume of oxygen will contain 
the same number ; and as the oxygen volume is 16 times as 
heavy as the hydrogen, it is clear that the weight of each 
molecule of oxygen will be 16 times that of each molecule 
of hydrogen. The molecules of hydrogen and oxygen each 
contain two atoms, hence the atomic weights will also be in 
the proportion of 16 to 1. 

As gases are decidedly affected by even slight changes in 
temperature and pressure, it becomes necessary to refer all 
observations to a standard condition. Under the English 
system of weights and measures this has usually been 60° F. 
for temperature, and 30 inches of mercury (about 15 pounds 
per square inch) for pressure. Under the French system the 
temperature is 0"^ C, (sometimes 15"^ C.) and 760 millimetres 
of mercury. This latter figure is practically the same as 30 
inches, and is the height of the barometer at the level of the 
sea. 

A study of the condition of the ordinary gases leads us to 
believe that the spaces between the molecules are very much 
greater than the molecules themselves. Ample room exists 
in any gas for adding atoms or molecules without increasing 
the volume. The phenomena of combination between gases 
seem to show that all molecules are of the same size ; at least 
it is known that the elementary gases combine in such a way 
as to produce a volume of gas which is equal to twice the vol- 



48 ELEMENTS OF CHEMISTRY. 

lime that would be occupied by one atomic iv eight of hydrogen. 
Tlie following instances are taken from among the commonest 
chemical compounds : 

One volume of H and one volume of CI combine and pro- 
duce tivo volumes of HCl. 

Two volumes of H and one volume of O combine and pro- 
duce two volumes of H2O. 

Three volumes of H and one volume of N combine and 
produce tivo volumes of NH3. 

In each of these cases it is seeii that the volume of the 
resulting combination is twice that of the one atomic w'eight 
of hydrogen. If the weights should be in grammes, then the 
resulting volume would be that occupied by two grammes of 
H ; if the weights should be in grains, then the resulting vol- 
ume would be that occupied by two grains of H ; and if the 
substances were estimated by volume alone, say in pints, then 
the resulting compounds would have the volume of two pints. 

The great majority of chemical compounds that have been 
examined conform to this law. A few exceptions are known, 
and, as mentioned above, some elements cannot be converted 
into gas, and thus cannot be examined on this point. It fol- 
lows, from this uniform condensation, that when the molecule 
contains many atoms the gas will be heavy, and, further, that 
its weight compared to hydrogen can be easily calculated. 

Some examples will make this plain : 

47 cubic inches of H, weighing 1 grain, v ill combine with 
47 cubic inches of CI, weighing 85.4 grains, and produce 94 
cubic inches (i. e. 47 X 2) of hydrochloric acid (HCl), weigh- 
ing 36.4 grains ; and by dividing this last result by 2 we get 
the weight of a quantity of hydrochloric acid equal to the 
one atomic weight of hydrogen — viz. 18.2. This figure, 18.2, 
represents, therefore, the density or sj^ecific gravity compared 
to hydrogen. 

94 cubic inches of H, weighing 2 grains, will combine with 
47 cubic inches of O, weighing 16 grains, and produce 94 



ELEMENTS OF CHEMISTRY, 49 

cubic inches of steam, H.2O, weighing 18 grains. If we 
divide 18 by 2, we get, as before, the density of steam com- 
pared to hydrogen — viz. 9. 

47 cubic inches of N, weighing 14 grains, will combine with 
141 cubic inches (47 X 3) of H, weighing 3 grains, and form 
94 cubic inches of ammonia, NH3, weighing 17 grains ; and 
this weight, divided by 2, gives 8.5 as the density of ammonia 
compared to hydrogen. 

These principles are employed in determining the formulae 
of bodies. N and O combine to form a body called nitric 
oxide, which is sometimes written NO and sometimes N2O2. 
The following calculation will show which is correct: 

The formula NO requires 

One volume of N = 14 

" " " = 16 

30 30 -^- 2 = 15, producing two 
volumes NO. 
The formula N2O.2 wdll require 
Two volumes of N = 28 
" " " = 32 

60 60 -f- 2 = 30, producing two 
volumes N2O2. 

In the first instance the formula would indicate a vapor 
fifteen times as heavy as hydrogen ; in the second case, 
thirty times as heavy. Experiment shows the first number 
to be correct, and therefore justifies the formula NO. 



11. RELATION BETWEEN SPECIFIC HEAT AND 
ATOMIC WEIGHT. 

The specific heat of any substance is the proportion 
between the amount of heat required to raise the body to 



50 



ELEMENTS OF CHEMISTRY. 



any temperature, and that required to raise the same weight 
of water to the same temperature. One pound of water 
requires thirty-three times as much heat to raise it to any 
temperature as mercury does ; the specific heat of mercury 
is therefore -3^3. 

Many of the elements show the interesting fact that mul- 
tiplying their specific heat and atomic weight together gives 
nearly similar numbers, as the follo\ving table shows: 



Element. 


Atomic weight. 


Specific iieat. 


Product. 


Na 


23 


0.2934 


6.75 


S 


32 


0.2026 


6.48 


Cu 


63.4 


0.0952 


6.04 


Zn 


65.2 


0.0956 


6.24 


As 


75 


0.0814 


6.10 


Br 


80 


0.0843 


6.75 


Au 


197 


0.0324 


6.38 


Hg 


200 


0.0319 


6.38 


Pb 


207 


0.0314 


6.50 



Some of the elements give difierent results in difierent con- 
ditions, and some give results that are entirely at variance 
W'ith the law. 



12- NUMERICAL RELATIONS OF THE ATOMIC 
WEIGHTS. 

Independently of the relations bet^veen the atomic 
weights and other quantities discussed in the preceding sec- 
tions, several attempts have been made to exhibit the rela- 
tions between the atomic w^eights themselves, especially 
between the w^eights of bodies belonging to the same group. 
Some of these attempts have been passed over as merely 
curious speculations ; others have been regarded as of value 
in classifying the elements, and even in deciding betv/een 
differing determinations of atomic weight. Among the most 
recent and most noticeable of these systems is the one known 
as 



ELEMENTS OF CHEMISTRY, 51 

Mendelejeff's Law of Periodicity. — It has recently 
attracted considerable attention, because it is supposed to 
point out the true classification of the elements, and to give 
indication of elements existing but yet undiscovered. The 
arrangement, as presented by Mendelejeff, is best shown by 
the table on the next page. 

Many gaps, however, are noticed ; some elements are placed 
out of the commonly-accepted arrangement ; others have new 
atomic weights assigned to them. The element gallium was 
not known at the time this system was published, and the 
fact that it fits one of the gaps is regarded as a proof of the 
value of the tables. Mendelejefi* has expressed the points of 
his system in a mathematical phrase, as follows : 

The jyroperties of elements, the constitution and 'properties of 
their combinations^ are periodic functions of the atomic lueights. 



52 



ELEMENTS OF CHEMISTRY. 



CO CD 05 05 
Xi lO lO O 



- o o v-" 



:5 ^ r^ 5c 



lO t^ 00 Oi 
Oi O^ G^i O:) 
1— ( 1— < 1— ( rH 

II II II II 

CO t^ -w ^ 



3 g 



O 

CO 



W 



o 

o 



02 







o 




00 


o 


O 


t^ 


1! 


il 


li 


!h 


o 


o 


^ 


Ul 


^ 



^ 



o 






3 I 



^ 



00 L':' 



f^ > 



12; 



^ 
OQ 



II II .11 






N 



00 o 









" i ^ rv] 



§ 00 

II CO 






OO 

rH 


g : 

(N : 


II 


II ; 


^ 


s ; 


C^. 




O 
00 

1— 1 


§?5 


II 


II II 


^ 





OO 


Ttl I 


t- 


o : 


T-K 


(M . 


1! 


II i 


^ 




H 


^ ' 






H^ 



fcXD 



c3 



c3 



CO 






CO 
CO 



3 



^ 



S 



feJO 



o 



o 
o 



bO 



•saijog 



C5 O 1— I c^ 



DESCRIPTIVE CHEMISTRY. 



A COMPLETE table of the elements, their atomicities, atomic 
weights and symbols, will be found at the end of the book. 
Before beginning Descriptive Chemistry a brief account will 
be given of the important groups. 

1. The Oxygen Group includes oxygen, sulphur, selenium 
and tellurium. They are electro-negative dyads, and possess 
the power of forming, with many elements, basic or acid 
compounds, according to the proportion in which they are 
combined. 

2. The Chlorine Group includes fluorine, chlorine, bromine 
and iodine. They are electro-negative monads, and are the 
only elements which form salts without the aid of some mem- 
ber of the oxygen group. For this reason they have been 
called the halogens, a word meaning "salt-formers.'' 

3. The Nitrogen Group includes boron, nitrogen, phos- 
phorus, arsenic, antimony, and probably vanadium, bismuth 
and gold. They are of uneven atomicity, generally triads or 
pentads ; their electrical relations are intermediate in charac- 
ter, neither strongly positive nor strongly negative. They 
form anhydrides, distinguished by the power of combining 
with water in two or more proportions, forming distinct acids. 
Several of them combine easily with hydrogen to produce 
bodies which have analogies to the members of the potas- 
sium group (q. v.). 

4. The Carbon Group includes carbon, silicon, titanium, 

5^ 53 



54 ELEMENTS OF CHEMISTRY. 

tin and some rarer elements. They are tetrads, and, like the 
nitrogen group, their electrical relations are intermediate. 
Boron is sometimes classed here, but it is a triad and belongs 
to the nitrogen group. 

5. The Potassium Group includes hydrogen, lithium, 
sodium, potassium, rubidium, caesium and silver. They are 
electro-positive monads, and — with the exception of hydrogen 
and silver, which differ in several material points from tiie 
rest of the group — have high affinity for the members of the 
oxygen and chlorine groups. With oxygen they produce 
powerful corrosive bases called the alkalies, and on this 
account are sometimes called the alkali metals. Hydrogen 
and silver are the only ones that occur free in nature. 

6. The Calcium Group includes calcium, barium, stron- 
tium and lead. They are electro -positive dyads, and form 
oxides which are slightly soluble in water, but much less 
caustic or corrosive than the alkalies proper, and are often 
called alkaline earths. Their sulphates, carbonates and 
phosphates are practically insoluble. 

7. The Zinc Group includes zinc, magnesium, cadmium 
and beryllium. They are never found free, but are tolerably 
easily reduced from their compounds. They are electro-posi- 
tive dyads, and form a definite oxide which is insoluble in 
water, not caustic, but capable of forming well-marked 
salts. 

8. The Iron Group is electro-positive, and includes alumi- 
num, iron, manganese, nickel, cobalt, chromium and prob- 
ably several other elements the chemistry of which is not well 
known. They are not found in the metallic state, except in 
small quantity. Most of them form tv/o sets of compounds, 
acting in one as dyads, in the other as double tetrads. Sev- 
eral form well-marked anhydrides. 

9. The Copper Group includes copper and mercury, elec- 
tro-positive dyads, resembling each other in the power of forming 



ELEMENTS OF CHEMISTRY, 55 



two sets of compounds, in one of which they act as dyads, and 
in the other apparently as monads. In the apparently monad 
condition they form chlorides insoluble in water, and are in 
this way partly related to silver. 

10. The Platinum Group. A number of elements which 
are found in association with platinum are usually grouped 
together under the name of platinum metals. These are plat- 
inum, palladium, iridium, rhodium, ruthenium and osmium. 
They do not, however, appear to be connected by any striking 
relations, and wdien their properties and compounds become 
better understood they will probably be distributed among 
the groups already described. Pt, Pd and Eu agree in some 
resjDects with tin ; Ir and Rh with iron ; Os with nitrogen. 

Unclassified Elements. Some of the elements are either 
so rare that their relations have not yet been satisfactorily 
studied, or their properties are such as to render it impossible to 
classify them satisfactorily under any system. Among these are 
molybdenum, zirconium, tantalum, tungsten, yttrium, thorium, 
erbium, uranium, cerium, lanthanum, didymium, gallium, in- 
dium and thallium. The brief descriptions that these need 
will be given in connection with those groups to which they 
seem to be related. 

An arrangement in series like that just given can never 
show the true relations of the elements. By a tabular form, 
such as is given on page 56, each element can be placed so as 
to show its relations to the others. In the table the elements 
that are distinctly electro-negative are printed in bold type; 
those distinctly electro-positive, in ordinary Eoman type ; those 
intermediate, in italic. 



56 



ELEMENTS OF CHEMISTRY. 





s 


a- 


be 
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ELEMENTS OF CHEMISTRY. 57 



Chlorine Group. This includes chlorine, bromine, iodine 
and fluorine. They are negative monads, and of high chem- 
ical affinity. They combine with oxygen in several propor- 
tions, assuming atomicities of three, five and seven, but the 
compounds are easily decomposed. Chlorine generally ex- 
pels bromine from combination, and bromine expels iodine. 

CHLORINE, CI, 35.46. 

Chlorine was discovered by Scheele in 1774. 

The name, derived from a Greek word meaning " green," 
w^as given by Davy. 

Sources. Chlorine is always found in combination. Its 
most abundant compound is common salt, NaCl, which is 
found in the animal, vegetable and mineral kingdoms. The 
chlorides of lead, silver and some other bodies are found 
as minerals. Of late years a considerable amount of potas- 
sium chloride has been obtained from the salt-mines of Stass- 
furth, Germany. Hydrogen chloride is occasionally found in 
volcanic regions. 

Preparation. Chlorine being extensively used in man- 
ufacturing chemistry, many processes for its preparation have 
been devised ; nearly all of them depend upon the oxidation 
of some chloride. Hydrogen chloride, hydrochloric acid, is 
generally used. The following include the processes best 
suited for the laboratory: 

(a) By heating a mixture of manganese dioxide and hydro- 
chloric acid, 

Mn02 + 4HC1 = MnCl^ -f • 2H,0 + Cl^. 

(6) By heating a mixture of common salt, sulphuric acid 
and manganese dioxide, 

MnO^ + 2NaCl + 2H,S0, = MnSO, + Na^SO, + 2H,0 + CI,. 

(c) By the action of hydrochloric acid upon potassium 
chlorate, potassium bichromate or bleaching-pow^der. These 



58 



ELEMENTS OF CHEMISTRY. 




methods are suitable for the preparation of small amounts of 
chlorine for use as a test. 

The process (6) is the most economical, (a) the most con- 
venient for laboratory-work. 

Exp, Mix in a flask about 
1 ounce of black oxide of 
manganese with 4 ounces of 
hydrochloric acid ; shake well, 
and heat the mixture gently. 
The chlorine is best collected 
by displacement. The opera- 
tion should be conducted on 
the small scale and in a well- 
ventilated place, as the gas 
is very irritating. Karrow- 
mouthed, stoppered bottles of 
about one pint capacity will 
answer very well for receiv- 
ing the gas. It cannot be collected over water or mercury. 

Properties. Chlorine is a greenish-yellow gas of a dis- 
agreeable and highly irritating odor. By a pressure of about 
60 pounds to the inch it condenses to a greenish liquid which 
has never been frozen. The gas is about two and a half times 
as heavy as air ; one litre weighs 3.1808 grms. ; water dis- 
solves about three volumes, acquiring the color and odor of 
the gas; the solution, known as chlorine water, does not keep 
well. 

The affinities of chlorine are very great. It combines 
with every element. It combines directly with most of the 
metals, decomposes water, and bleaches and destroys many 
organic substances. Its affinity for hydrogen is increased 
by light. 

Exp. A lighted taper put into a jar of chlorine continues to burn, 
but with a dark red flame and the escape of clouds of smoke. The 
chlorine has combined with the hydrogen of the wax, and not with 
carbon, hence the abundant liberation of the latter. 

Exp. Powdered antimony dropped into chlorine takes fire at once, 



ELEMENTS OE CHEMISTRY. 59 

and produces dense, irritating clouds of antimony chloride. Dutch 
leaf, a sort of brass, is also instantly burned up. 

Exp. Paper dipped in oil of turpentine takes fire spontaneously in 
chlorine, producing a red flame and a dense cloud of smoke. This 
experiment requires pretty pure chlorine and good turpentine. 

Exp. The bleaching power of chlorine is easily shown by pouring 
some solution of cochineal or litmus into a jar of the gas. The color 
is almost instantly removed. Pieces of calico may also be quickly ** 
bleached by placing them, in a wet state, in contact with the gas. 

Exp. A small quantity of the gas as it comes from the evolution- 
flask should be allowed to bubble through Avater. If a small cj^uantity 
of this liquid be shaken in a bottle containing hydrogen sulphide, the 
odor of this gas will disappear. 

The last two experiments show the bleaching and disinfect- 
ing applications of chlorine. It is, however, rarely used in the 
form of gas, on account of the obvious inconvenience. It is 
usually employed in the form of bleaching-powder, made by 
passing the gas into slaked lime. The body so produced is 
described among the calcium salts. It is easily decomposed 
by dilute acids, yielding its chlorine ; even the carbonic acid 
of the air will act upon it. It is generally employed in solu- 
tion, and is often incorrectly called chloride of lime. 

Chlorine does not bleach unless moist, and it is believed 
that a decomposition of water first occurs, and that the oxy- 
gen thus set free is the active agent, 

H,0 + CL,--2HCl + 0. 

The powerful action of chlorine is utilized occasionally for 
the decomposition of ores. 

Gen. Chem. Eel. In the chlorides the chlorine is electro- 
negative and monatomic. It is capable, how^ever, of assum- 
ing electro-^oositive relations and higher atomicities, and in its 
compounds with oxygen shows both these changes. It is also 
capable of replacing hydrogen, atom for atom, giving rise to 
an important and extensive series of substitution compounds, 
which are considered in connection with Organic Chemistry. 



60 



ELEMENTS OF CHEMISTRY. 



The chlorides are generally less numerous than the corre- 
sponding oxides ; for instance, we know two oxides of hydro- 
gen, but only one chloride. 

Hydrochloric Acid, Muriatic Acid, Spirit of Salt, 

HCl. This substance was long known in an impure form. 
Basil Valentine (fifteenth century) described the pure acid, 
and Davy in 1810 showed its composition. 

Sources. Hydrochloric acid occurs in the gases evolved 
from volcanoes and in solution in 'the waters of some moun- 
tain-streams of South America. 

Preparation. The acid may be formed by the direct 
union of its elements, but this method has only theoretical 
interest. The practical process is the action of common salt 
and sulphuric acid, according to the following reaction: 

2NaCl + H2SO4 = Na^SO^ + 2HC1. 

This reaction requires a high temperature. In ordinary 
experiments and on the small scale the reaction is 

NaCl + H2SO, = NaHSO^ + HCl ; 

by w^hich, from a given amount of sulphuric acid, only half 
the quantity of hydrochloric acid is obtained. This form of 
the process is therefore costly. 

Exp. One ounce of com- 
mon table salt is mixed 
with twice its weight of 
strong sulphuric acid in a 
flask provided with a de- 
livery-tube in the ordinary 
manner as shown. The 
hydrochloric acid comes 
off freely, and may be 
collected by downward dis- 
placement, as in the prep 
aration of chlorine, or 
passed into water. Heat 
may be used, but the tube 
must be taken from the water when the heat is withdrawn. 




ELEMENTS OF CHEMISTRY, 61 

Properties. Hydrochloric acid is a colorless gas of a 
strong pungent odor and poisonous to animals and plants. 
Its density is 18.181 ; 1 litre weighs 1.63 grms. It may be 
liquefied by a pressure of about 600 pounds to the inch. It 
does not burn nor support ordinary combustion, but some 
substances burn in it, forming chlorides. Its most important 
property is its solubility in water, which at low temperature 
will absorb nearly 500 volumes, producing a strongly acid 
solution, which is the common hydrochloric or muriatic acid. 
The strongest form usually sold contains 43 per cent, by 
Aveight of the gas. When pure it is a colorless, fuming, 
strongly acid liquid, but the commercial forms are usually 
yellow, from the presence of iron. 

Gen. Ghem. Rel. Hydrochloric acid is rather w^eaker 
than sulphuric or nitric acid, but is used largely as a solvent. 
It generally acts by forming chlorides. When the body dis- 
solved is an element, free hydrogen generally escapes ; but 
when compounds are dissolved, the hydrogen usually com- 
bines with the substance displaced by the chlorine. 

In this w^ay oxides dissolve in hydrochloric acid and form 
chlorides and water ; sulphides form hydrogen sulphide, etc. 
The following reactions are instances : 

Zn + 2HCl = ZnCl, + H2. 
ZnO + 2HC1 = ZnCL, + H^O. 
FeS + 2HC1 = FeCl^ +H,S. 

With oxides more rich in oxygen (Mn02,Fe203Cr03) the 
action is dependent upon the temperature and other condi- 
tions. Sometimes the whole of the chlorine is retained, in 
other cases a portion escapes. 

FeA + 6HC1 = Fe^Cle + 3H,0. 
MnO, + 4HC1 = MnCl2 + 211J0 + Cl^. 

Tests. Hydrochloric acid produces, wdth ammonia, w^hite 
fumes of iSTHiCl. In common vrith all the chlorides, it pro- 

6 



62 ELEMENTS OF CHEMISTRY. 

duces, with silver nitrate, a white curdy precipitate of silver 
chloride, soluble in ammonia. 

A mixture of about three parts nitric with five parts hy- 
drochloric acid has been long used under the names aqua regia 
and nitro-muriatic acid. It dissolves gold and platinum, and 
owes its efficacy in part to the free chlorine which is formed 
by the oxidizing action of the nitric acid upon the hydrogen 
of the muriatic. 

Compounds of Chlorine and Oxygen. Three of these 
are known in the free state : 

CI2O Hypochlorous anhydride. 

CI2O3 Chlorous anhydride. 

CIO2 Chlorine dioxide. 

Several others are known only in combination, and in these 
we have a well-marked and important series : 

HCIO Hypochlorous acid. 

HCIO2 Chlorous 

HCIO3 Chloric 

HCIO, Perchloric 

Hypochlorous anhydride, CI2O, is formed when chlorine is 
passed over mercuric oxide, 

HgO + Cl,=.CLO + HgGl2. 

The combination of oxygen and chlorine will not take place 
w^hen the two elements are mixed under ordinary conditions. 
The action in this case may be regarded as an instance of the 
influence of the nascent state. Hypochlorous anhydride is 
absorbed by water, and is supposed to form hypochlorous acid, 
HCIO, w^hich has been used as a bleaching agent, especially 
for removing ink-stains, 

Exj:). Shake a few grains of finely-powdered mercuric oxide with 
some chlorine water. The odor of chlorine will be replaced by that 
of hypochlorous acid, and the liquid will easily remove stains of writing 
without seriously injuring the paper. Other hypochlorites may be 



ELEMENTS OF CHEMISTRY, 63 

formed by the action of chlorine upon metallic oxides or hydrates at a 
low temperature. (See Calcium Hypochlorite.) 

Chloric Acid, HCIO3. If the action of chlorine npon 
metallic oxides or hydrates be at a temperature of over 60"^ 
F. (15.5° C), chlorates will be produced, according to the fol- 
lowing reaction : 

6KH0 + Cls = KCIO3 + 5KC1 + 3H,0. 

The chlorate and chloride are separated by difference of solu- 
bility in water. Chloric acid may be obtained from the 
chlorates by stronger acids, but it has no practical value. 

The chlorates are useful for the large amount of oxygen 
which they contain, and which they give up easily when 
heated. Potassium chlorate is the substance from w^hich 
oxygen is usually prepared. It is used largely in fireworks. 
Perchloric acid is obtained by heating dilute chloric acid. 
The per chlorates resemble the chlorates. 

The other compounds of chlorine and oxygen have no 
practical importance. 

Chlorine combines ^vith nitrogen to form a body called 
nitrogen chloride, of which the composition is somewhat un- 
certain. It is an oily liquid, which decomposes very easily 
and with a violent explosion. 



BROMINE, Br, 80. 

Sources, Bromine occurs in sea-water and sea-plants, in 
brine-springs and in a fe\v minerals. Its compounds are gen- 
erally associated with those of chlorine. Considerable quan- 
tities have of late been obtained from brine-springs in western 
Pennsylvania. Bromine was discovered by Balard in 1826. 
The name is derived from a Greek word meaning ^' bad 
smell." 

Preparation. Bromine is prepared by processes analo- 
gous to those of chlorine — acting upon bromides by means of 



64 ELEMENTS OF CHEMISTRY, 

oxidizing agents, such as a mixture of sulphuric acid and 
manganese dioxide. It may also be directly expelled by the 
superior affinity of. chlorine. 

Exp. Dissolve some potassium bromide in a little water ; add a pinch 
of manganese dioxide and a few drops of sulphuric acid. Heat gently, 
and dark red vapors of bromine will soon be evolved. The reaction is 
precisely like that for chlorine : 

2KBr + Mn02 + 2H2SO^ = K^SO^ + MnSO^ + 2H2O + Br2. 

Exp. To a solution of potassium bromide in water add a few drops 
of chlorine water, and shake. The bromine will be set free and color 
the water yellowish. If some ether be now poured in and shaken for 
a few moments, tlie bromine will leave the water and dissolve in the 
ether, which will form a red layer on the surface of the water. The 
reaction is 

KBr + Cl=3KCl + Br. 

The free bromine is usually dissolved in potassium hydrate, 
by ^yhich a mixture of potassium bromate and bromide is 
produced. The reaction is similar to that which occurs in the 
preparation of potassium chlorate (page 63). This mixture 
being heated, the bromate loses oxygen and forms bromide. 

Properties. Bromine is a dark red liquid, which at or- 
dinary temperatures evolves red vapors of an excessively 
irritating and disagreeable odor. The liquid is three times 
as heavy as water, and boils at 145° F. (63° C.) and freezes 
at — 12° F. ( — 25° C). It is soluble in water, and is often 
conveniently used in that form. Its chemical properties are 
similar to those of chlorine, but are not so energetic. It 
bleaches vegetable colors, and by decomposing water acts 
as an oxidizing agent. A number of its compounds are used 
in medicine. 

Eo:p. The affinity of bromine may be easily sjipwn by placing a few 
drops on a small piece of phosphorus, which will at once be ignited. 

Gen. Chem. Rel. The chemical relations of bromine are 
almost exactly those of chlorine. It combines energetically, 
forming bromides, of which those of hydrogen, potassium and 



ELEMENTS OF CHEMISTRY, 65 

ammonium are the most important. In these compounds the 
bromine is a monad. It also forms oxygen compounds analo- 
gous to those of chlorine, but they have little interest. 

Tests. Bromides may be recognized by the production of 
the red vapor of bromine by the action of free chlorine or of 
a mixture of manganese dioxide and sulphuric acid. With 
solutions of bromides silver nitrate gives a light yellow 
precipitate of silver bromide which is slightly soluble in 
ammonia. 

Hydrogen Bromide, Hydrobromic Acid, HBr. This 
substance cannot be conveniently prepared by the action of 
sulphuric acid upon a bromide, which would be the theoret- 
ical method, because the sulphuric acid is decomposed by 
the hydrogen, and instead of the reaction 

2KBr + H2SO, = K,S04 + 2HBr, 

w^e have the HBr acting on another portion of the sulphuric 
acid and giving 

2HBr + H2SO4 -= 2H2O + SO2 + Br^. 

Hydrobromic acid is obtained by using a mixture of 
phosphorus, powdered glass and bromine, or by the action of 
phosphoric acid upon a bromide. It resembles hydrochloric 
acid in its properties, and is used in medicine. 

Bromic Acid, HBrOg, and Hypobromous Acid, HBrO, 

are also known. They closely resemble the corresponding 
chlorine compounds. 



IODINE, I, 127. 



Sources. Iodine occurs in association with bromine and 
chlorine in sea-water and sea-plants. The latter are burned, 
and the ashes, called kelp^ contain various iodides. 



66 ELEMENTS OF CHEMISTRY. 

Iodine was discovered by Courtois in 1811. The name 
means "violet-colored," and refers to the vapor. 

Preparation. Iodine is prepared by processes similar to 
those for bromine, either by the action of chlorine or of a 
mixture of manganese dioxide and sulphuric acid. The 
reactions are 

KI + C1 = KC1 + I, 
or 

2KI + MnO^ + 2H,S0, = K,SO, + MnSO^ + 2H,0 + I^. 

The reactions may be shown by substituting an iodide for a 
bromide in the experiments described on page 64. 

Properties, Iodine forms bluish-black crystalline masses 
wdth a metallic lustre. It evaporates slowly at ordinary tem- 
peratures, melts at 225^ F. (107"^ C), and boils at 347° F. 
(175^ C). The vapor has a deep violet color and a peculiar 
odor, somewhat like that of chlorine, but not so irritating. 
The solid dissolves slightly in water — much more freely in 
w^ater containing potassium iodide, and in alcohol, ether and 
carbon disulphide. It has some bleaching and oxidizing 
powers. One of its important properties is the power of 
producing a blue color with starch. For this action the 
iodine must be in the free state ; the iodides give no color. 

Exp, Prepare some starch solution by boiling common starch with 
enough water to make a thin liquid. To one portion of this liquid 
add a few grains of potassium iodide. To another portion add a 
drop or two of solution of iodine. The fii'st solution will remain color- 
less ; the second will become deep blue. Dip slips of paper into the 
colorless solution, and expose them to either the vapors of nitric acid, 
chlorine or ozone ; a blue color will be immediately produced, because 
the iodine is set free. Papers prepared in this manner are therefore 
used as tests for the vapoi-s just mentioned. 

Exp. The affinity of iodine is shown by adding a few grains to a 
small piece of phosphorus. Combustion occurs in a few seconds, and 
if a large bell jar be set down over the mass a quantity of iodine vapor 
will be collected in it. 

Gen. Chem. Rel. The chemical relations of iodine are 
substantially the same as those of chlorine and bromine. 



ELEMENTS OF CHEMISTRY. 67 

Tests. Iodides are recognized by the production of a 
violet vapor when treated with a free chlorine or a mixture 
of manganese dioxide and sulphuric acid. A solution of 
silver nitrate gives, with soluble iodides, a yellow^ precipitate, 
silver iodide, insoluble in ammonia.. Free iodine is easily 
recognized by its action on starch. 

Hydriodic Acid, Hydrogen Iodide, HI. This is pre- 
pared by methods similar to those used for hydrogen bromide, 
which body it closely resembles. It is used in medicine. 

Two compounds with oxygen are known, of which iodic 
acid, IIIO3, has some little importance from being used as a 
test for morphia, which produces with it a brown color. 

By the action of strong ammonia upon pow^dered iodine a 
brownish substance is produced, which was supposed to be 
nitrogen iodide, but probably contains hydrogen. It is easily 
handled while wet, but when perfectly dry explodes, with a 
loud report, on the slightest touch. 

Exp. Put a few grains of iodine into a watch-glass and pour on 
enough strong ammonia to cover the mass. Crush the iodine with a 
glass rod, and allow the mixture to remain quiet for five minutes ; then 
pour off the ammonia, and put the brown powder in small portions on 
pieces of filter-paper. After about half an hour the powder will be 
dry, and will explode on the slightest touch. 



FLUORINE, F, 19. 

Sources. Fluorine is tolerably abundant as fluor spar, 
CaFa, and cryolite, GXaF, AI2F6, and some rarer minerals. 
It exists in the stems of grasses and in bones and teeth. 

Preparation and Properties. Fluorine has never been 
satisfactorily prepared. Its high affinities and its special 
power of acting on glass and on metals render it difficult 
to experiment with it. It has been described as a yellow 
gas, and also as colorless. 



68 ELEMENTS OF CHEMISTRY. 

Gen. Chem. Rel. It combines with every known element 
except oxygen, and bears close resemblance to chlorine in 
most of its relations. It is remarkable for its affinity for 
silicon. 

Hydrogen Fluoride, Hydrofluoric Acid, HF. This 
body is easily prepared by acting on calcium fluoride, CaF.^, 
with sulphuric acid. The operation must be performed in 
vessels of lead or platinum. The pure HF is a gas, but it is 
commonly seen as a strong solution in water. It acts power- 
fully, especially on siliceous materials. It is used for etching 
designs on glass. 

Exp. Prepare a glass plate, flowing over it some wax or paraffine, and 
cutting a way the coating in any design. Invert the coated plate over a 
leaden dish in which have just been placed some strong sulphuric acid 
and enough powdered calcium fluoride to make a thick paste. The 
action m.av be assisted by a gentle heat, but care must be taken not to 
melt the wax. After ten or fifteen minutes the uncovered parts of the 
glass will be found corroded. The wax can be gotten off by warming 
the plate. 

Strono; solution of hydro o:en fluoride is now sold in sfutta- 
percha bottles, upon which it has no action. 

Tests. Fluorine compounds are recognized by their power 
of producing hydrogen fluoride when heated with sulphuric 
acid. The hydrogen fluoride is easily detected by its action 
on glass. 



Potassium Group. The potassium group proper mcludes 
potassium, sodium, lithium, rubidium, csesium. They are 
electro-positive monads, and are of such high affinities that 
they never occur in nature in the free state. Their com- 
pounds are nearly all soluble in water. Their oxides and 
hydrates are powerfully corrosive, and are known as the 
caustic alkalies. Hydrogen and silver, being positive monads, 
are also classed in this group, although they differ from the 
rest in some points. 



ELEMENTS OF CHEMISTRY. 69 

HYDROGEN, H, 1. 

Sources. Hydrogen exists in water and in all animal and 
vegetable substances. It was discovered by Cavendish in 1776. 
The name means " producer of water." 

Preparation. 1. By the action of an electrical current 
on water or various acids. The familiar experiment of pass- 
ing a current through water acidulated with sulphuric acid, 
although called "the decomposition of water/' is really the 
decomposition of the acid. Pure water requires a very 
powerful current. 

2. By the action of elements of high affinity on water or 
acids. With acids the action generally occurs without the 
aid of heat ; with water, sodium and potassium act in the cold ; 
iron, magnesium, zinc, etc. require a high temperature. Car- 
bon may also be used, and is especially suitable when very 
large quantities are required. 

3. By the action of alkaline solutions on a mixture of zinc 
and iron filings or on aluminum. 

4. By heating a mixture of potassium formate and potas- 
sium hydrate, 

KCHO, + KHO = K2CO3 + H2. 
This method yields a pure gas, and was used by Pictet in his 
exjDeriment on its liquefaction. 

Ex'p. A piece of sodium amalgam [q. v.) is lield 
in a spoon under an inverted test-tube filled with 
water and standing on the pneumatic trough. The 
gas collects in the tube, and may be tested ns ex- 
plained below. The water beconaes alkaline from the 
formation of caustic soda, 

Na + H2O = NaHO + H. 
Exip. Magnesium ribbon is folded once or twice, and placed in a 
small hard-glass tube, one end of which is partially drawn down to a 
jet, the other attached to an apparatus for producing steam. Steam is 
passed through until the tube and ribbon are free from condensed moist- 
ure. The metal is then strongly heated at the extreme point ; it takes 





70 ELEMENTS OF CHEMISTRY. 

fire, producing an oxide and free hydrogen, which latter can be burned 

at the jet. 

Mg + H,0 = MgO + H,. 

Exp. Fragments of zinc are introduced into the gas 
bottle, and dilute sulphuric or hydrochloric acid added ; 
tlie gas comes off freely. 

Zn + H,SO, = ZnSO, + H^. 
Being very light and insoluble in water, it may be col- 
lected either by the pneumatic trough, as shown under 
oxygen, or by upward displacement ; that is, allowing the 
tube to touch the bottom of a wide-mouthed bottle or 
jar inverted over the jet. 

A mixture of hydrogen with air explodes Vvdien lighted, hence no ex- 
periment should be made until all the air is driven out of the evolution- 
bottle. The best test is to collect a small quantity in an inverted test- 
tube by displacement. After the gas has passed in for about half a 
minute, the tube should be removed, and, still keeping it inverted, a 
light should be applied to its mouth ; a sharp explosion, extending at 
once through the tube, indicates the presence of air ; a slight explosion 
at the mouth of the tube only, and a faint flame moving gradually up 
the tube, show the gas to be pure. 

Properties. Pure hydrogen is colorless, tasteless and 
odorless. It is the lightest body known, a litre weighing 
0.08961 grm. 100 cubic inches weigh 2.14 grains. It can 
be liquefied only by intense cold and pressure. 

The important properties of hydrogen may be show^n by the 
following experiments : 

1 . Lighted at the mouth of the delivery-tube, it burns with a pale 
blue, but very hot, flame. If the jet is of glass, the flame becomes yel- 
low ; a dry vessel held over it becomes coated with moisture, which is 
tlie sole product of the combustion. 

2. A stout wide-mouthed bottle, or belter a small tin vessel, filled with 
a mixture of the gas and air gives a loud explosion on being ignited. 

3. Soap-bubbles blown with the gas rise rapidly in the air. 

4. A large light vessel being counterpoised on a delicate balance will 
be thrown decidedly out of balance by substituting hydrogen for tlie 
contained air by displacement. On placing the vessel with the mouth 
upward, the hydrogen quickly escapes and the equilibrium is restored. 



^ ?:lements of chemistry. 71 

Hydrogen, tliougli not poisonous, Avill not sustain life ; 
small quantities can be inhaled without danger, and pro- 
duce a peculiar change in the voice. For this the gas must 
be absolutely pure, which that made from commercial articles 
never is. 

Gen. Chem. Rel. Hydrogen is electro-positive, and is a 
standard for atomicity, atomic and molecular weight and den- 
sity. It combines with many elements. As explained in the 
section on nomenclature, it is regarded as the essential element 
of acids. Keeping in view the fact that the affinity of sub- 
stances is diminished by volatility, it will be seen that the 
hydrogen compounds should be easily decomposable, and 
should be active chemical agents. Such a body as H2SO4 
is the most active of the sulphates, because its positive ele- 
ment (hydrogen) is of low affinity, and is displaced by a large 
number of bodies. 

Water, H2O. Yv^hen two volumes of hydrogen and one 
volume of oxygen are combined, complete condensation takes 
place and water is formed. When w^ater is decomposed by 
the electrical current, two volumes of hydrogen and one vol- 
ume of oxygen are always obtained. Since oxygen is six- 
teen times as heavy as hydrogen, the proportion by weight 
will be 2 to 16 or 1 to 8. The formula H^O indicates that 
the molecule contains two atoms of hydrogen and one atom 
of oxygen. When the combination of the two gases is per- 
formed at a temperature of 212° F. (100° C), the water re- 
mains as steam, equal in volume to the original hydrogen. 
Tlie theoretical relations of this fact have been considered in 
the section on combination by volume. The composition of 
water hy weight has been established with great accuracy by 
passing hydrogen over hot copper oxide ; the oxygen is ab- 
stracted from the copper and combines with the hydrogen. 
The water so formed is collected and weighed ; the loss of 
weight of the copper oxide gives the quantity of oxygen taken 
up, and the difference is the hydrogen. The actual result of 



72 ELE3IFSTS OF CHEMISTRY. 

such an experiment, conducted ^vith every precaution to insure 

accuracy, is — 

Hydrogen 11.11 

Oxygen 88.89 

100.00 
which is substantially 1 to 8. 

Properties. Pure water is odorless and tasteless, and in 
large masses distinctly blue. Under ordinary pressure it 
freezes at 32° F. (0° C.) and boils at 212° F. (100° C). It 
dissolves many bodies, solid, liquid and gaseous, and is ab- 
sorbed by many substances. Porous bodies, for instance, ex- 
posed to moist air increase in weight considerably by absorb- 
ing water. These effects are not generally regarded as due to 
chemical affinity. Solution of solids in water is generally 
attended with the production of cold, as may be shown by 
making a solution of Epsom salt or ammonium chloride. 
The solution of gases is apt to be attended wdth the produc- 
tion of heat. The solvent power of water is quite extensive, 
though very different for different bodies. As a rule, the sol- 
ubility of solids is increased by heat, that of gases diminished. 
Gases exhibit great differences ; some— 6. g. hydrogen and 
oxygen — dissolve very sparingly ; ammonia and hydrochloric 
acid, on the other hand, are largely dissolved. Gases may 
all be expelled by thorough boiling. When strong solutions 
are prepared by heat, the liquid on cooling usually deposits a 
portion of the dissolved substance in a crystalline form. 

Exp. Bring some water to boiling, and introduce, 
by small portions at a time, potassium chlora^te until 
no more dissolves ; pour the solution into a thin glass 
beaker, and the chlorate will be continually deposited 
in fine scales until the liquid is quite cold. Lead 
iodide treated in the same way gives even a better 
effect. 

Water is extensively distributed in nature. 
Besides being collected into large masses, 
oceans, lakes, etc., it exists in suspension in the atmosphere, 
in most minerals and in all animal and vegetable tissues. 




ELEMENTS OF CHEMISTRY. 73 

Some living structures, such as succulent fruit, jelly-fish, etc., 
consist almost entirely of water. In all these natural condi- 
tions water is impure. Rain contains ammonium salts, espe- 
cially nitrates and nitrites, and when collected in populated 
places is often decidedly impure ; rivers and springs are con- 
taminated generally with sulphates, chlorides, carbonates and 
organic substances. The total quantity ordinarily dissolved 
varies from five to thirty grains to the gallon. When the 
quantity greatly exceeds this, and especially when peculiar 
substances, such as iron or sulphur, are present, it constitutes 
a mineral water. Sea-water is yery rich in mineral substances, 
and may be regarded as a mineral water. 

The more important varieties of natural waters are — 
Alkaline or carbonated ivaters, containing yarious carbonates 
in solution, generally with a quantity of free carbonic acid. 

Sard waters, in which a decided amount of magnesium or 
calcium salts is present. The chemical relations of these 
waters will be hereafter explained. 

Chalybeate waters, containing iron, generally as ferrous car- 
bonate with excess of carbonic acid. 

Sidphur loaters, containing sulphuretted hydrogen and other 
sulphides. 

Acid waters, containing some of the stronger acids in the 
free state. 

Saline or aperient waters, having large amounts of chlorides 
and sulphates. 

The substances thus dissolved influence the health of those 
regularly drinking the water, but as to the exact nature of 
the effects little is known. Springs of chalybeate, alkaline 
and other mineral waters are resorted to by invalids, but how 
much of the apparent beneficial action is due to the w^ater, 
and how much to change of scene, diet and other conditions, 
is a mooted point. "With regard to ordinary drinking water, 
its composition may vary within wide limits without appreci- 



74 



ELEMENTS OF CHEMISTRY. 



able effect upon those who drink it. According to the gen- 
erally accepted method, the important points to be determined 
in the analysis of water are — total amount of dissolved matter, 
degree of hardness, amount of chlorine, nitrates and nitrites, 
and of organic matter. The difficult problem is the determi- 
nation of the organic matter. By the term are meant the ani- 
mal and vegetable substances that get in with the waste, drain- 
age and sewage which all flowing water receives. These sub- 
stances occur only in minute quantities even in impure water, 
but appear to be capable of doing much harm. 

Purification of Water. Filtration through porous ma- 
terials, paper, charcoal, sand, etc., will remove suspended im- 
purities. Animal charcoal and spongy iron remove some of 
the dissolved matters, but distillation is the only method of 
preparing absolutely pure y»^ater. 




Gen. Chem. Rel. A very large number of substances 
form, with water, definite chemical compounds, in some of 
which the water unites without changing ; in others the mole- 
cule H2O seems to be broken up. Of the first kind of com- 
bination instances are seen in common crystals. Copper 
sulphate, for instance, has the formula CuSO^, but the blue 
crystals sold as copper sulphate contain, in addition to this 
formula, a large amount of water. This water is derived 
from that in which the copper sulphate was dissolved. It is 
an essential part of the crystal, for if we drive out all of it 
the mass is converted into a white powder. Chemical an- 



ELEMENTS OF CHEMISTRY. 75* 

alysis shows that the composition of the blue substance is 
CuSOi + 5H2O. Water that is in this way part of a mole- 
cule and essential to a crystalline form is called water of 
CRYSTALLIZATION. Substances that do not contain it in such 
a state of combination are said to be anhydrous. Some 
common salts form crystals containing large amounts of 
water ; sodium carbonate in its commercial form, Na^COs -f- 
IOH2O, contains over fifty per cent, w^ater. Water of crys- 
tallization is usually easily driven out by heat. 

The second form of the chemical action of water is where 
it is apparently decomposed, its two elements associating 
themselves independently with the elements of the other 
body. If we mix w^ater with about three times its weight of 
common quicklime, a violent action, attended with produc- 
tion of much heat, ensues, and a dry pow^der results, from 
which no appreciable amount of water can be expelled except 
by a red heat. If this compound contained water in an un- 
changed form, a moderate heat would drive it all out ; hence, 
chemists have regarded the compound not as CaOjH^O, but 
as CaH202, which is an entirely new body, containing really 
neither quicklime nor w^ater. A considerable number of 
oxides are capable of uniting thus with water and forming 
bodies know^n as hydrates. 

Perhaps the most scientific view of these hydrates is to 
regard the water as acting the part of an acid (it might 
indeed be called hydric acid), and just as CaSO^ is, calcium 
sulphate, CaH202 will be calcium hydrate. Water, in fact, 
might be written HHO, the first H being replaceable by an 
element, according to the usual law of atomicity. A portion 
of the hydrogen must always remain, or the body would 
become an oxide. Thus, if potassium were to act upon water 
according to the reaction K2 + H2O = K2O + H2, or calcium 
were to act according to the reaction 

Ca + H2O = CaO + H2, 

the bodies produced would not be hydrates, but oxides. 



76 ELEMENTS OF CHEMISTRY. 

The oxides which, by addition of water, produce hydrates 
are called anhydrides. By subtracting H2O from any hy- 
drate we may reproduce the corresponding anhydride. Many 
of the common acids may in this way furnish anhydrides, 
some of which are interesting bodies : 

Sulphuric acid. Sulphuric anhydride. 

H,S04 — H2O =S03 

In the same manner the student may deduce 

Sulphurous anhydride, SO2, from sulphurous acid. 
Carbonic " CO2, from carbonic " 

If the acid contains but one atom of hydrogen, we must, 
of course, double the formula before subtracting. Hence 

Nitric acid. Nitric anhydride. 

2HNO3 — H2O =NA 

Similarly we deduce 

Nitrous anhydride, N2O3, from nitrous acid, 
Phosphoric " P2O5, " phosphoric acid. 

We may proceed in the same w^ay with other hydrates : 

Calcium hydrate. Calcium anhydride. 

CaH202 — H^O =CaO 

As before, w^hen the hydrate contains but one atom of 
hydrogen we double the formula : 

Potassium hydrate. Potassium anhydride. 

2KH0 — H2O =K20 

The term anhydride generally refers to those bodies which 
yield acids by addition of w^ater. Those which yield hy- 
drates capable of neutralizing acids are generally called bases. 

By exposing water to the action of nascent oxygen it can 
be made to take up an additional atom, and becomes II2O2. 

Hydrogen Dioxide, H2O2. This body, sometimes called 
oxygenated water, is prepared by liberating oxygen in the 



ELEMENTS OF CHEMISTRY. 77 

presence of water, as when barium dioxide is dissolved in 
dilute hydrochloric acid : 

BaO^ + 2HC1 + H,0 = BaCl^ + H^O + H,0.,. 

A dilute solution may be easily obtained in this way, but the 
concentrated liquid is very difficult to prepare. It is a color- 
less, transparent, oily liquid, nearly one-half heavier than 
water ; it is without odor, has a bitter taste, blisters the skin 
and bleaches organic colors. It is decomposed by heat and 
by many chemical substances, often explosively. It dissolves 
in ether, and the solution has been used in medicine and for 
bleaching the hair. 



POTASSIUM, K, 39. 

Sources and Preparation. Potassium occurs in many 
rocks and soils ; from these it is absorbed by land-plants, in 
the ashes of which potassium carbonate is found. Large 
deposits of nitrate and chloride also occur. It is best pre- 
pared by heating the carbonate with charcoal. Discovered 
by Davy in 1807. 

Properties and Gen. Ohem. Rel. Potassium is quite 
soft, and the freshly-cut surface has a silver lustre, but it 
quickly tarnishes in the air. It decomposes w^ater rapidly, 
the escaping hydrogen being so highly heated as to take 
fire, burning with a purple flame due to the presence of 
potassium. Specific gravity, 0.865. It is highly electro- 
positive, and forms several oxides, only one of which is 
important. 

Potassa, K2O, is obtained by oxidizing potassium in dry 
air. It is generally seen as hydrate. 

Potassium Hydrate, Caustic Potassa, KHO, is made by 
boiling potassium carbonate with slaked lime. 

CaH.O^ + K.COa = 2KH0 + CaCOs. 



78 ELEMENTS OF CHEMISTRY. 

The solution is filtered from the insoluble CaCOs, evaporated 
to dryness, the residue *fused and cast in sticks. Caustic 
potassa is a white solid, very soluble in water, powerfully 
alkaline and corrosive. 

Potassium Carbonate, K2CO3, Salt of Tartar. This is 
found in the ashes of land-plants, being produced by the 
action of heat upon the compounds of potassium with organic 
acids. The ashes are treated with water ; the solution thus 
obtained yields, on evaporation, the impure carbonate termed 
pearl-ash. Pure potassium carbonate is white, soluble in 
w^ater, alkaline and moderately corrosive. 

Acid Potassium Carbonate, KHCO3, Salceratvs, is prepared 
by adding carbonic acid to the normal carbonate. It is a 
white crystalline body, soluble in water, and is used in efier- 
vescing mixtures, but acid sodium carbonate has of late 
years substituted it to a great extent. It is often called 
bicai^bonate. 

Potassium Sulphate, K2SO4. This is a residue of some 
manufacturing operations. It forms hard, colorless, six- 
sided crystals, which 'are not very soluble in cold water. 

Acid Potassium Suljjhate, KIISO4, is also a by-product in 
certain operations. It is sour and strongly acid to test-pajDer. 
It is often called bisulphate, and is used as a substitute and 
adulterant for cream of tartar. 

Potassium Nitrate, KI^Os, Mtre, Saltpetre, is found on 
the surface of the soil in India, and is prepared artificially 
by allow^ing nitrogenous matter to decay in the presence of 
wood-ashes (containing KoCOs) and lime, and in a full supply 
of air. It appears that ammonia is first formed and then 
oxidized. The crude nitre, extracted by water, must be care- 
fully purified, when it appears in large crystals, soluble in 
water. It melts below redness, and when further heated 
decomposes, giving ofi* oxygen and nitrogen, and leaving 
K2O. Potassium nitrate is used in gunpowder and fire- 
works as a source of oxygen. Gunpowder consists of about 



ELEMENTS OF CHEMISTRY, 79 

75 parts nitre, 15 parts charcoal and 10 parts sulphur. The 
reaction is approximately 

4KNO3 + a + S = K.COa + K.SO, + N, + 2CO2 + CO. 

The N, GO2 and CO occupy at the moment of explosion 
about 1200 times the bulk of the powder, and the explosive 
action of gunpowder is due to this sudden expansion in 
volume. 

Potassium Chlorate, KCIO3. The method of manufac- 
ture is given on page 63. The salt crystallizes in flat, tabular 
crystals. It melts below a red heat ; at a little higher tem- 
perature gives off all its oxygen, leaving KCl. It is not very 
soluble in cold water. It is used largely as a source of oxygen, 
also in m.atches and firew^orks, and as a medicine. 

Exp. Some crystals of potassium chlorate and a few pieces of phos- 
phorus are put into a wineglass nearly filled with water, and sulphuric 
acid poured directly upon them by means of a funnel-tube. Tlie chlo- 
rate decomposes, furnishing various oxides of chlorine, which cause the 
phosphorus to burn brilliantly under the water. 

Exp, Powdered sugar mixed with about three times its weight of 
potassium chlorate will burn when touched with a drop of sulphuric 
acid. 

Exp. A mixture of two parts potassium chlorate with one part of 
potassium ferrocyanide and one part sugar makes white gunpowder, 
which explodes very easily and very violently. Only a small quantity 
should be made at once, and ihe ingredients should be powdered sep- 
arately and mixed gently. 

Potassium Chloride exists in sea-water and in the saline 
deposits at Stassfurth, Germany. It resembles common salt. 
It forms an insoluble double salt with platinic chloride, 
2KC1 + PtCU. 

Potassium Bromide is made a-ccording to the method given 
on page 64. It forms cubical crystals soluble in water. 

Potassium Iodide is prepared like the bromide, which it 
closely resembles, but is rather a finer white. It is easily 
soluble in water. 



80 ELEMBNTS OF CHEMISTRY. 

KBr and KI are often made by first preparing the cor- 
responding iron compound, and decomposing it with potas- 
sium carbonate. 

Tests. Potassium compounds are mostly soluble in water. 
A few, however, are so slightly soluble as to afford us service- 
able tests. 

1. Platinum chloride produces a yellow crystalline precip- 
itate of potasso-platinum chloride, 2KC1 + PtCl^. 

2. Tartaric acid gives a Avhite crystalline precipitate of 
acid pota^ssium tartrate, KHC4H4O6. 

Brisk stirring with a glass rod promotes the formation of 
both precipitates, 

3. Potassium compounds give to flame a color which is a 
mixture of red and violet. 



SODIUM, Na, 23. 

Sources. Common salt, NaCl, is the principal source. 
Sodium compounds are widely distributed, occurring even in 
common dust. The ashes of sea-plants contain sodium car- 
bonate. Sodium was discovered by Davy in 1807. 

Preparation and Properties. It is prepared in a man- 
ner similar to potassium, which it closely resembles, but is a 
little heavier and not so easily oxidized. Its chemical relations 
and the properties of its compounds are also much like those 
of potassium. 

Sodium Hydrate, NaHO, Caustic Soda, is prepared by a 
process similar to that used for caustic potash, using Na2C03 
instead of K2CO3. Caustic soda is usually sold in cylindrical 
sticks. It is soluble in water, and is very strongly alkaline and 
corrosive. 

Sodium Carbonate, Na^COy, Sal Soda, was formerly ob- 



ELEMENTS OF CHEMISTRY. 81 

tained from the ashes of sea-plants, but is now made princi- 
pally by the action of chalk and charcoal upon sodium sul- 
phate. It forms large crystals, having the composition 
Na^COa + lOHoO, very soluble in water, and often called 
washing soda. On exposure to air these crystals effloresce — 
that is, lose water and fall to a white powder. 

Acid Sodium Carbonate. NaHCOs, Baking Soda. This 
body is produced in the same manner as acid potassium car- 
bonate, which it closely resembles. It is now much used in 
effervescing mixtures like Seidlitz powders and the common 
baking-powders, which latter are usually a mixture of cream 
of tartar and baking soda. Alum and acid potassium sulphate 
are often used in the inferior grades as a substitute for the 
cream of tartar. The action of the powder is due to the sud- 
den evolution of a large volume of carbon dioxide, 

KaHCOa + KHCH^Oe = XaKQH A + H,0 + CO,. 

Sodium Sulphate, Glaubers Salt,l>lRSOi,i$ a by-product 
in the manufacture of nitric and muriatic acids. It forms 
large clear crystals which contain ten molecules of water of 
crystallization. They effloresce in dry air, and are remark- 
able for being more soluble in water at 93° F. (34° C.) than 
at any other temperature. The principal use of sodium sul- 
phate is as a source of sodium carbonate. 

Sodium Nitrate, XaXOs, is found in large beds in north- 
ern Chili, and termed Chili saltpetre. It is used as a manure, 
and also in the preparation of nitric acid. It is not used in 
gunpowder, on account of its tendency to absorb water. 

Sodium Chloride, Common Salt, XaCl, is too well known 
to need description. It occurs in thick beds in various parts 
of the world, and is also prepared from sea-water by evapor- 
ation or freezing, and from certain brine-springs by evapor- 
ation. It dissolves in about the same amount in hot and 
cold water. 

Sodium Phosphates. The only important form is disodium 



82 ELEMENTS OF CHEMISTRY, 

acid phosphate, NaaHPOi, which is used in medicine and also 
as a test for magnesium. 

Sodium Anhydroborate, 2NaB02 + B A, commonly 
called sodium biborate or borax, is found in certain lakes in 
Thibet and in California. It is also made by melting sodium 
carbonate with boric acid. It forms hard crystals, which dis- 
solve in about twelve times their weight of water and form an 
alkaline solution. Borax is much used as a solvent for metallic 
oxides, especially in blowpipe analysis. It is used for cleaning 
metals in soldering. 

Sodium Silicate, made by fusing sand or pulverized quartz 
with an excess of sodium carbonate, constitutes soluble glass, 
which dissolves in boiling water. It is used as a cement and 
in soaps. 

Sodium Thiosiilphate, lsra2S203, much used in photography 
under the name hyposulphite. Its solution possesses the power 
of dissolving most of the salts of silver, except Ag2S, which 
are insoluble in v/ater. 

Sodium Sulphite, Na2S03, is used as a substitute for sulphur- 
ous acid in preventing fermentation. 

Tests. The only convenient test for sodium is the strong 
yellow color that its compounds give to flame. 

Lithium, Li, 7. Discovered by Arfvedson in 1817. It is 
found in many substances, but only in small quantity. Its 
principal sources are some rather rare minerals. Lithium 
resembles potassium. Sp. Gr. 0.593. Its salts resemble those 
of potassium and sodium, but lithium carbonate is but spar- 
ingly soluble in water. Lithium compounds have been used 
in gout and similar chronic diseases ; and, as many spring 
waters contain traces of lithium, the medicinal action of such 
waters has been supposed to be due to it, and much nonsense 
and quackery have been developed in connection with the 
analysis of them. 



ELEMENTS OF CHEMISTRY, 83 



Tests. Lithium imparts a crimson color to flame, which 
is the most convenient and delicate method of detecting its 
compounds. 

Caesium, Cs, 133, and Rubidium, Kb, 85.4, were discovered 
by Bunsen and Kirchoff in 1860 by the spectroscope. They 
exist only in small quantity in some mineral waters and in a 
few plants. They are strongly positive and closely resemble 
potassium. Caesium gives a blue color to flame ; rubidium, a 
dark-red color. 



SILVER, Ag, 108. 



Sources. Silver occurs native — that is, in the free state — 
in moderate abundance, also as sulphide, chloride and other 
forms. It is often present in small amounts in lead ores. 
Silver was known to the ancients. 

Preparation. Silver is easily reduced to the metallic 
state, most of its compounds being decomposed by heat. 
When existing in small quantities in ores, it may be taken 
out by agitating the powdered material with mercury, which 
dissolves the silver (amalgamation), and this amalgam, being 
drawn off" and distilled, leaves the metallic silver. When 
compounds like sulphides or chlorides are reduced, it is some- 
times necessary to add iron scraps to liberate the silver before 
adding the mercury. 

Properties. Silver is white and highly lustrous, easily 
worked into plates and wire, and the best conductor of heat 
and electricity known. Specific gravity, 10.5. It resists the 
action of oxygen and of caustic alkalies, but is attacked by 
sulphur and sulphides and by nitric acid. Solutions of silver 
salts are decomposed by heat, light and electricity, and by 
many forms of organic matter, especially when mixed with 
alkalies. The sensitiveness of its salts to light is the basis of 



84 ELEMENTS OF CHEMISTRY, 

photography. It melts at 1681"^ F. (916° C). For coinage 
it is usually alloyed Vvith copper. In some of its properties — 
e. g. its high specific gravity, resistance to the action of the 
air and the slight solubility of its oxide and carbonate — it is 
related to lead and copper. 

Silver Oxide, Ag20, cannot be formed directly, as, although 
oxygen is absorbed by melted silver, no combination is formed 
on cooling. It is a black powder, usually made by heating 
silver hydrate, AgHO, which latter is produced when silver 
nitrate is mixed with an alkali. 

AgNOs + Is^aHO = Is^aNOs + AgHO. 
Silver Sulphate, Ag2S0i, is sometimes used in analysis. 

Silver Nitrate, AgNOs, Lunar Caustic, is easily made by 
dissolving the metal in nitric acid. The reaction is similar to 
that with copper. 

Ag3 H- 4HNO3 = 3 AgNOs + 2H2O + NO. 

Silver nitrate forms colorless crystals, very soluble in water, 
and, when mixed with organic matter, blackened by light. It 
fuses at 426° F. (219° C), and is often cast in sticks for use 
as a caustic. The property of forming a black, difficultly 
soluble precipitate with organic matter is utilized in the manu- 
facture of hair-dyes and marking-ink. 

Silver Chloride, AgCl, is found as a mineral, and is easily 
formed artificially by adding any chloride to silver nitrate. 

KaCl + AgKOs == AgCl + NaNOs. 

It forms a heavy white precipitate like curdled milk, turning 
violet in the light, especially if organic matter be present, 
forming a subchloride, Ag2Cl. It is insoluble in most acids, 
but dissolves freely in ammonia and in sodium thiosulphate. 

A number of other silver compounds have been described, 
but have but little importance. 

Silver Salts in Photograjyhy, — The action of light upon silver 



ELEMENTS OF CHEMISTRY. 85 

compounds is mostly an operation of reduction, sometimes to 
the metallic condition. The presence of organic matter aids 
the change. In some of the compounds the effect of the light 
is not attended with any change of color. 



Oxygen Group. This group includes oxygen, sulphur, 
selenium and tellurium. They are electro-negative dyads, 
and have a wide range of affinity, combining with many 
bodies in several proportions. With many substances they 
unite in small proportion to form bases, and in large pro- 
portion to form anhydrides. 

OXYGEN, O, 16. 

Sources. Oxygen exists in water, air, all animal and 
vegetable tissues and in the great majority of minerals. It 
constitutes over half the matter composing the earth. It 
w^as discovered by Scheele and Priestley in 1774. The name 
means " producer of acids." 

Preparation. 1. The oxides of mercury and of some other 
elements are decomposed by heating. This method is of little 
practical value, but is interesting, as it w^as the means of the 
discovery of the gas, HgO = Hg + O. 

2. Certain compounds of manganese and barium when heated 
in a current of air absorb oxygen, and give it out in a current 
of steam. By alternating these two currents large quantities 
of oxygen may be obtained. Such processes are not suitable 
for laboratory-work. 

3. The chlorates, nitrates and some rarer salts are decom- 
posed by heat, giving off large quantities of oxygen, but not 
always quite pure. Potassium chlorate is by far the most 
suitable. Used alone, it requires a high temperature, but 
when mixed with about one-quarter of its weight of man- 
ganese dio:^ide a heat of about 500^ F. (260° C.) is sufficient. 

8 



86 



ELEMENTS OF CHEMISTRY. 




The exact manner in which manganese dioxide acts has not 
been explained. 

Exp. Mix thoroughly 4 parts potassium chlorate with 1 part manga- 
nese dioxide, and heat the mixture in any suitable vessel. One ounce of 

potassium chlorate yields 
nearly two gallons of the 
gas. It may be collected 
in a glass bottle held over 
the end of the tube, this 
bottle having been pre- 
viously filled with water 
and then inverted into the 
bowl, after closing the 
mouth of it Avith a card 
or glass plate. No water 
will escape until bubbles 
from the tube are passed 
into it, which, on account 
of their lightness, ascend 
and displace the water. 
When the water is all out, remove the bottle, and place it mouth down- 
ward in a saucer of water, replacing it with another bottle previously 
filled with water, and repeat this process until the evolution of gas 
ceases. The first bubbles that pass over consist of air contained in the 
test-tube, and the pure gas quickly succeeds. 

The reaction in this experiment concerns the potassium 
chlorate only, which is simply decomposed : 

KClOs^-KCl + Os. 

The arrangement depicted in the cut is called the pneu- 
matic trough, and is extensively used for collecting gases. 
Water is the liquid generally employed, but in some cases 
mercury is used. As long as the vessels in which the gas 
is collected are kept inverted and their mouths below the 
surface of the water (or mercury), no gas can escape or air 
get in. 

Properties. Pure oxygen is colorless, odorless and taste- 
less ; it is one-tenth heavier than air, one litre weighing 1.43 
grm. It is continually being absorbed by living , animals in 



ELEMENTS OF CHEMISTRY. 



87 




the process of respiration, to which function it is essential. 
It is also consumed in all ordinary combustion. The pure 
gas causes considerable excitement of the vital functions of 
animals and greatly increased action in ordinary flames, but 
does not, as a rule, produce spontaneous combustion. 

Exp. A taper or splinter of wood lighted and blown out 
in such a way as to leave a glowing coal is instantly re- 
lighted, with a slight explosion, on putting it into the gas. 
The experiment may be repeated several times. 

Ejj). a bit of bark or knot of charcoal ignited at one 
point and plunged into the gas burns brilliantly, producing 
a colorless gas which combines with water and forms an 
acid. 

Exp. Sulphur burns in oxygen with moderate brilliancy, producing 
a colorless, highly irritating gas, which in combination with water pro- 
duces an acid. A picture painted with a solution of quinine sulphate is 
almost invisible by ordinary light, but becomes visible when illuminated 
by burning sulphur; the exphmation of this effect belongs to physics; 
it is called fluorescence, and is shown by many substances. 

Exp. Phosphorus burns in the gas with great brilliancy, producing 
dense white clouds, which rapidly absorb water and produce a power- 
ful acid. 

It will be noticed that in the foregoing experiments acids 
have been produced by the combustion. Lavoisier supposed 
that oxygen w^as necessary to the production of an acid ; the 
present name of the gas means " acid-producer,'^ and expresses 
this view. According to the opinion of modern chemists, 
hydrogen is the essential element of acids, and the following 
experiments will show that the combination of oxygen may 
produce bodies very different from acids : 

Exp. Magnesium ribbon ignited and plunged into oxygen 
burns rapidly and brightly, producing a bulky white pow- 
der, insoluble in water and of alkaline properties. 

Exp. One end of a thin steel ribbon (watch-spring) is 
wrapped with a few turns of cotton thread and then dipped 
into melted sulphur or wax. This end being lighted, the 
ribbon is put into oxygen ; the metal quickly takes fire, 
produces an abundance of sparks, and from time to time drops hot 




ELEMENTS OF CHEMISTRY. 



globules to the bottom of the jar, which often fuse themselves into the 
glass. A layer of three or four inches of water or an inch of sand will 
generally prevent the breaking of the jar. The product is black, in- 
soluble in water and destitute of acid properties. 

Sodium, potassium and zinc turnings also burn in oxygen with more 
or less brilliancy. 

The explanation of the production of acids in the first set 
of experiments is that the water, which is always present in 
these cases, forms with the product of combustion a new sub- 
stance. The combinations of oxygen are called oxides ; in the 
case of the burning sulphur the resulting gas has the formula 
SO2, sulphur dioxide, and if the materials were perfectly dry 
no acid would be formed. In the presence of water we have 
the reaction HoO + SO2 = H2SO3, sulphurous acid. Similarly, 
the charcoal produces CO2, which, uniting v>ith water, produces 
H2CO3, carbonic acid. The same principle applies to the 
phosphorus experiment. 

On the other hand, the metals manganese, sodium, etc. 
form oxides which, so far from being acids, are really power- 
ful neutralizers of acids and are said to be alkaline or basic. 
They combine with water, producing compounds which retain 
the alkaline character. In this way we have MgO + H2O = 
MgH202, ]Sra20 + H20 = Na2H202. Further explanations 
will be found in the section on Water. 

Gen. Chem. Eel. Oxygen combines with every other ele- 
ment except fluorine, and with many in several proportions. 
The chemical relations of these oxides are dependent in part 
upon the number of oxygen atoms present. The oxides of 
manganese may be taken as examples : 

MnO, Powerful base. 

Mn203, Weak base. 

Mn02, Indifferent. 

MnOs, Forming an acid (anhydride). 

These instances illustrate the general law that small propor- 
tions of oxygen tend to produce bases, high proportions anhy- 



ELEMENTS OF CHEMISTRY. 89 

drides or acid-forming oxides, and intermediate proportions 
bodies of uncertain or indifferent ciiaracter. Some elements 
are apparently incapable of yielding bases. These form with 
oxygen, in low jDroportions, neutral oxides. This is shown by 



uitrogen series : 




N.O, 


Indifferent. 


NO, 


Indifferent. 


NA, 


Acid-forming. 


NO,, 


Doubtful. 


N.O5, 


Acid-forming. 



Oxygen is a dyad, and is generally considered the most 
electro-negative element, but under some circumstances chlo- 
rine seems to be superior in this respect. It is slightly soluble 
in water, and upon this fact depends the existence of most 
forms of aquatic life. 

Substances which take away oxygen from its combinations 
are called reducing agents ; those which add oxygen, oxidiz- 
ing agents. 

Tests. Besides the power of relighting a taper, free 
oxygen may be recognized by its turning brown a mixture 
of caustic soda and pyrogallin, and by converting colorless 
nitric oxide into red peroxide. 

Ozone. Oxygen is susceptible of a modification of some 
of its properties without chemical change. The study of this 
subject was begun in 1840 by Schonbein, and very many re- 
searches have since been made, without, however, completely 
explaining the condition. The modified oxygen is called 
" ozone," from a Greek word meaning " to smell," on account 
of its marked odor. 

Ozone may be prepared in several ways : 

1st. By a succession of electrical sparks through air or 
oxygen. Its peculiar odor is observed when an electrical 
machine is put into active operation. 

8* 



90 ELEMENTS OF CHEMISTRY. 

2d. By the slow oxidation of phosphorus and of turpen- 
tine and other essential oils. 

3d. By the decomposition of \Yater by the galvanic cur- 
rent. 

4th. By the action of acids upon certain bodies rich in 
oxygen. 

By all these methods only a small proportion of the oxy- 
gen is converted into ozone. 

Exp, Place a few crystals of potassium permanganate in a vride- 
mouthed bottle and add a few drops of sulphuric acid. A peculiar 
odor is noticed ; the evolved gas will tarnish mercury and silver, and 
turn blue a piece of paper soaked in a solution of potassium iodide and 
starch. This last effect is due to the setting fi^ee of the iodine by the 
superior afSnity of the ozone for the potassium. Organic matter is 
also acted upon powerfully. 

Ozone is heavier than oxygen, is soluble in water, and is 
converted into common oxygen by heat and by contact with 
some oxides. It is generally present in the atmosphere, espe- 
cially in open country-places. It is considered an important 
natural disinfectant. 

Another modification of oxygen, called antozone, has been 
supposed to exist, but this is considered by many chemists to 
be hydrogen dioxide, II2O2. 



SULPHUR, S, 32. 

Sources. Sulphur occurs native — i. e, in the fre^ state — 
in volcanic regions, also in combination, forming sulphides 
and sulphates, and in animal and vegetable structures. 

Preparation. Commercial sulphur is prepared by melting 
or distilling the native sulphur or some of the sulphides. It 
presents itself in two forms : roll sidphur or brimstone, made 
by casting the melted sulphur in moulds ; and flowers of sid- 
2')hur, made by condensing the distilled sulphur in a cool 



ELEMENTS OF CHEMISTRY. 



91 



chamber. Lac sulphuris, or milk of sulphur, is a finely- 
divided medicinal form, obtained by dissolving common sul- 
phur in milk of lime, and precipitating by an acid. 

Properties. Sulphur assumes several allotropic forms, 
varying especially in color and solubility ; it is dimorphous 
— i. e, crystallizes in two forms, octahedral and prismatic. 
Ordinarily, sulphur is brittle, yellow and soluble in carbon 
disulphide, but by being suddenly cooled from near its boil- 
ing-point it becomes plastic, dark-colored and insoluble. AH 
varieties are insoluble in water, highly combustible, fusible 
at about 250° F. (121° C.) and boiling at 836° F. (447° C). 
It is a non-conductor of electricity, and becomes highly 
electrical by friction. 

Exp. A small quantitv of sulplmr is placed in a flask and heated 
slowly. It melts to a thin, amber-colored liquid. On continuing the 
heat the liquid gradually becomes thick, and at about 450° F. (232° C.) 
it is so tenacious that it can scarcely be 
poured out of the vessel. Heated still 
further, it becomes thin, and finally boils. 
Just before the sulphur begins to boil, pour 
it into cold water, when it will form dark 
brown, semi-elastic masses. If the sulphur 
remaining in the flask be heated to the 
boiling-point, a dark red vapor is produced, 
in which certain substances — e. g. Dutch leaf 
— burn easily. 

Exp. Dissolve some sulphur in a small 
quantity of carbon disulphide, and allow 
the solution to evaporate in the open air. 
hedra will be deposited. 

Exp. A few ounces of sulphur are fused in a Hessian crucible, and 
then allowed to cool until a film of solid forms on the surface. Break 
a small hole through this and pour out the liquid contents. On break- 
ing the crucible a mass of prismatic crystals vnll be found. 

Gen. Chem. Rel. Sulphur forms an important group of 
compounds — ^the sulphides. In these it is electro-negative 
and usually diatomic. With the members of its own group it 




Transparent yellow octa- 



92 ELEMENTS OF CHEMISTRY, 

combines in several proportions, showing atomicities of two, 
four and six, and perhaps even higher. In association with 
oxygen and chlorine it is regarded as electro-positive. In 
general its compounds are analogous in composition to those 
of oxygen, and as many oxides act as bases toward the or- 
dinary acids, so the corresponding sulphides act as bases 
toward what are called the sulphur acids. Thus we have 

K2O + CO2 = K2CO3 Potassium carbonate. 

K2S + CS2 = K.CSs " sulphocarbonate. 

In such compounds the sulphur is substituted for the oxygen, 
atom for atom, and the name is formed by affixing the syllable 
"sulph" to the name of the acid. A few of these sulphur 
salts are very important. 

Sulphur has many important uses. It is employed in medi- 
cine as an alterative and externally for skin diseases. It is 
used in the arts for vulcanizing caoutchouc and in the manu- 
facture of gunpowder. Match-sticks are tipped with it to 
make the friction composition ignite the wood more surely. 

Sulphur forms two compounds with hydrogen : 

II2S Hydrogen sulphide or sulphuretted hydrogen. 
II2S2 Hydrogen disulphide. 

Hydrogen Sulphide, H2S. Discovered by Scheele in 1777. 
This substance is a gas. It exists in solution in some spring 
waters, also in the emanations from volcanoes and decomjDosing 
animal and vegetable matters. It is sometimes produced by 
the action of organic matter upon sulphates. Calcium sulphate, 
CaSOi, by losing its oxygen becomes CaS, and this, by the action 
of carbonic acid, yields the gas, CaS + H2CO3 =: CaCOg + H2S. 
Hydrogen sulphide is much used as a test, and is frequently 
made in the laboratory by acting upon sulphides with strong 
acids. Ferrous sulphide and sulphuric acid are much used. 
FeS + H2SO, == FeSO, + H2S. ' 

Exy. Introduce into a gas-bottle some ferrous sulphide in small frag- 
ments, and pour over it some dilute sulphuric or hydrochloric acid. 



ELEMENTS OF CHEMISTRY. 93 

The hydrogen sulphide is liberated freely. As it is only slightly heavier 
than air and rather soluble in water, it is difficult to collect either by 
displacement or over water. 

Properties. Hydrogen sulphide is a colorless gas, con- 
densible by moderate cold and pressure. It has a strong 
odor like rotten eggs, is easily combustible, burning with a 
pale blue flame and producing sulphurous acid, H2SO3. Water 
at ordinary temperature dissolves about three volumes, acquir- 
ing the odor and chemical properties of the gas. The im- 
portant property of hydrogen sulphide is its power of precip- 
itating many elements as sulphides. These precipitates being 
generally distinct in color and highly insoluble, their produc- 
tion is not only a test for the presence of such bodies, but also 
a means of separating them from solution. 



Exp. As illustrations, solutions of copper sul- 
phate, mercuric chloride, tartar emetic and zinc 
sulphate may be precipitated either by a current 
of the gas or by its aq[ueous solution. The zinc 
sulphate requires the addition of a few drops of 
ammonia. 

When pure hydrogen sulphide is required it is generally 
obtained by heating a mixture of hydrochloric acid and anti- 
mony sulphide. Sb^Ss + 6HC1 =- 2SbCl3 + SH^S. 

Hydrogen sulphide is a powerful reducing agent ; solution 
of potassium permanganate is rapidly decolorized by it. A 
mixture of potassium bichromate and hydrochloric acid is 
changed into green chromic chloride. 

Tests. Hydrogen sulphide is recognized by its smell and 
by its blackening paper soaked in lead acetate solution. As 
the gas is a frequent product of decomposition, the leakage 
of sewer-gas may sometimes be detected by this test. 

Hydrogen Bisulphide, H2S2. This substance may be pre- 
pared by boiling together lime and sulphur, forming calcium 
disulphide, and pouring the solution into dilute hydrochloric 



94 



ELEMENTS OF CHEMISTRY. 



acid. The hydrogen disulphide separates as a yellow oily 
liquid of a disagreeable odor. It decomposes easily. 



Compounds of Sulphur with Oxygen. — Sulphur forms 
with oxygen a number of acid-forming oxides or anhydrides, 
most of which are known only in the hydrated condition — 
that is, as acids : 



liydridf 


i^ 




Acid. 


Name. 


SO 






H,SO, 


Hyposulphurous 


SO, 






H2SO3 


Sulphurous. 


S03 






H,SO, 


Sulphuric. 


s,o, ^ 






H2S2O3 


Thiosulphuric. 


S.05 






H,S,Oe 


Dithionic. 


S305 


not 

> 


yet 


H^S^Oe 


Trithionic. 


S.05 


obtained. 


H,SA 


Tetrathionic. 


S505 , 






H,SA 


Pentathionic. 



The first member of this series is the true hyposulphurous 
acid, the commercial hyposulphites being really salts of thio- 
sulphuric acid, hence properly called thiosulphates. Most of 
the members of the above series are of limited interest. 

Sulphur Dioxide, Sulphurous Anhydride, SO2. This 
substance is found in the emanations from volcanoes and fre- 
quently in the air of towns, being derived in the latter case 
from the sulphur in coal and coal gas. It is the usual prod- 
uct of the burning of sulphur or the sulphides in air or in 
oxygen, and is generally so made on the large scale. For 
laboratory operations it is most conveniently obtained by de- 
oxidizing sulphuric acid. The experiment requires strong 
acid and considerable heat. The substances which produce 
the best results are not soluble in the dilute acid. Copper, 
jxiercury, charcoal, silver, sulphur and other bodies may be 
used ; the first mentioned is the best for a small experi- 
ment. The sulphur dioxide which exists in the atmosphere 
of towns is slowly oxidized to sulphuric acid. 



ELEMENTS OF CHEMISTRY. 



95 




Exp. Strong sulphuric 
acid and some copper 
turnings or twisted cop- 
per wire are put into a 
flask and heated care- 
fully. The gas does not 
come oif until the tem- 
perature gets rather high. 
It may be collected by 
downward displacement, 
as shown under chlo- 
rine. 

The pneumatic 
trough cannot be used, as the gas is very soluble in water. 
To show this properly, the end of the delivery-tube may be 
dipped in some water in a beaker, when it will be found that 
most of the bubbles will be taken up by the liquid. This 
absorption must be carefully watched, or the water may be 
drawn back into the hot sulphuric acid. 

The reaction in the preparation of sulphurous acid is rather 
diiScult to understand. When strong positives, like zinc or 
magnesium, are put into acids, the usual result is the expul- 
sion of hydrogen. With zinc and sulphuric acid we get 
Zn + H,S0, = ZnS0i + H2. With bodies of less positive 
character a portion of the oxygen of the acid is removed, 
and water, sulphurous anhydride and a sulphate are formed. 
Copper gives 

Cu + 2H2SO, =- CuSO, + 2H,0 + SO2. 

Mercury and silver also give similar effects. Carbon and 
sulphur also deoxidize the acid, but no sulphates are formed, 
as these bodies cannot form salts. 

Carbon and sulphur give, respectively, the following reac- 
tions : 

C + 2H2SO, = 280^ + 2H2O + CO2. 
S + 2H2SO, = 3S0, + 2H,0. 

The carbon reaction is the most economical, but the admixed 



96 ELEMENTS OF CHEMISTRY. 

CO2 is objectionable. Sulphur dioxide may be made by heat- 
ing an intimate mixture of manganese dioxide and powdered 
sulphur. 

. Mn02+S, = S02 + MnS. 

Properties. It is a colorless gas, of the well-known 
irritating odor of burning matches. It can be condensed 
to a colorless liquid by a cold 0° F. ( — 18"^ C). A mixture 
of snow and salt answers quite well as a means of obtaining 
sufficient cold. The liquid so obtained is sulphur dioxide, 
SO2, and not sulphurous acid. It boils at 14° F. (—10° C.) 
and freezes at — 105° F. ( — 76° C). Sulphur dioxide passed 
into water forms sulphurous acid, H^O + SO 2 = H2SO3, which 
remains in solution, giving the liquid all the common prop- 
erties of an acid ; vegetable colors are first reddened, then 
bleached. The solution is also a pow^erful reducing agent, 
and is much used for that purpose. 

Although, theoretically, w^e make a distinction between the 
anhydride and the acid, yet, practically, we disregard this dis- 
tinction, and for most experiments may use either the gas or 
the solution in water. 

The principal properties of this body may be easily shown 
by the following experiments : 

Dip a lighted taper in a jar in which the gas has been collected by 
displacement. The flame is immediately extinguished. 

Suspend a delicately colored flower, somewhat moist, in a jar of the 
gas. Tlie colors bleached by this agent are not entirely destroyed, and 
by exposure to the action of weak ammonia are often restored, with 
curious modifications. 

Add some solution of sulphurous acid to solutions of 

(a) potassium bichromate mixed with hydrochloric acid ; 

{h) potassium permanganate. 

(a) will be changed to green chromic chloride ; 

[h) will be wholly decolorized. These effects are due to the re- 
ducing action of the sulphur dioxide, which thus becomes converted 
into sulphuric acid. 



ELEMENTS OF CHEMISTRY, 97 

The anhydride, free acid and its salts are antiseptic agents 
— that is, prevent putrefaction and fermentation, especially 
the latter. For this reason the vapors of burning sulphur 
are extensively used for fumigating ships and other places in 
which infectious diseases may exist. Wine- and beer-casks 
are also purified by sulphur, and the sulphites are added to 
fermented liquor to prevent further change. The acid is 
supposed to act by killing the minute living structures which 
are nearly always developed in decomposing and fermenting 
substances. 

Sulphur dioxide and hydrogen sulphide decompose each 
other according to the following reaction: 

2H,S + SO, = 2H,0 + S3. 

The experiment may be easily performed by passing currents 
of the two gases into a small bottle. 

Gen. Ohem. Rel. The salts of sulphurous acid are called 
sulphites ; monads, of course, form two compounds, acid and 
normal. Thus, potassium gives us 

Acid potassium sulphite. Potassium sulphite. 
KHSO3. K2SO3. 

Dyads give but one sulphite. From calcium we - have 
only CaSOs. 

Tests. The odor and bleaching power of the free acid 
and the reducing properties of the sulphites are sufficient 
means of detection. 

Sulphur Trioxide, Sulphuric Anhydride, SO3. This 
body is obtained by distilling Nordhausen sulphuric acid 
(q, V,), and by the action of phosphoric anhydride upon 
common sulphuric acid. The latter reaction is a simple 
dehydration. 

H,SO, + P,05 =- H,P,Oe (= 2HPO3) + SO3. 

Several other methods of making it are known. 

Properties. , Sulphuric anhydride is a soft, white, odor- 
9 



98 ELEMENTS OF CHEMISTRY. 

less solid in long, silky crystals like asbestos. Exposed to 
the air, it absorbs water rapidly and becomes converted into 
sulphuric acid. When dropped into water tile energy of com- 
bination is so great that a hissing noise is produced. The 
dry substance is destitute of corrosive properties, and is now 
sent into commerce in sealed iron boxes for use in certain 
manufacturing operations. It is occasionally employed as a 
means of drying gases and for special purposes in chemical 
research. It has a specific gravity of 1.95, melts at 65° F. 
(18.3° C.) and boils at 95° F. (35° C). 

Sulphuric Acid, Hydrogen Sulphate, Oil of Vitriol, 
II2SO4. This substance was probably known to Geber in the 
eighth century, and was certainly known to Basil Valentine in 
the fifteenth century. It is now made in large quantities in 
almost all parts of the civilized world, and it has been said by 
a technologist that the material prosperity of a country may 
be judged of by the extent of its sulphuric acid manufacture. 

Sources. Sulphuric acid occurs free in waters of volcanic 
and mining districts, and sometimes in the air of towns, being 
in the latter case derived from the oxidation of sulphurous 
acid. It also occurs in the saliva of certain dnimals. The 
compounds of sulphuric acid (sulphates) are of frequent oc- 
currence. Calcium and barium suljDhates are abundant min- 
erals ; sodium sulphate occurs in many natural waters. 

Preparation. The original method of preparation was 
the distillation of the sulphates, especially the ferrous sul- 
phate, FeSO^, which was produced by the oxidation of iron 
pyrites, FeSa. The process is still used for special purposes, 
as the acid so produced is more concentrated than the ordi- 
nary commercial article. The method by which the common 
acid is made depends upon the powder of one of the oxides 
of nitrogen to act as a carrier of oxygen from the air^ to sul- 
phurous acid. The outline of the practical process is as fol- 
lows : Vapors of nitric and sulphurous acids are mixed with 
steam and air in a large leaden room, the floor of which is 



ELEMENTS OF CHEMISTRY, 99 

slightly inclined and covered by a few inches of water. The sul- 
phurous acid is derived either from the burning of raw sulphur 
or the roasting of pyrites ; the nitric acid, from the action of 
sodium nitrate on sulphuric acid. The chemical changes are 
somewhat complicated, and are not wholly understood. The 
nitric acid changes some sulphurous acid to sulphuric, becom- 
ing itself converted into nitric oxide, NO, by this action. This 
NO takes oxygen from the air, and forms NO2, which oxidizes 
more sulphurous acid, and is thus again converted into NO, 
and again acted upon by the air. It will be seen that a small 
quantity of nitric acid will be sufficient to oxidize large quan- 
tities of sulphurous acid. The presence of large excess of water 
is essential to the reactions, hence steam, or water in a fine 
spray, is thrown continuously into the room. The above de- 
scription includes only the principal reactions ; the following 
series of equations show more exactly the changes occurring : 

SO2 + H^N^Oe = H,SO, + 2NO2. 
The steam acts upon the NO2 thus : 

3NO2 + H2O == H.N^Oe + NO. 
The NO takes O from the air and becomes NO2, w^hich together 
with the nitric acid just produced oxidizes more sulphurous 
acid, reproducing the NO, and the changes go on anew. 

The method may easily be shown experimentally : 

Exp, A wide-mouthed quart bottle is provided, with a cork perforated 
for four tubes. To these tubes are attached a flask for generating sul- 
phurous acid, a bottle for evolving nitric oxide {q. v.) and a flask for 
furnishing steam ; the fourth tube is left open to the air. Sulphurous 
acid and nitric oxide are produced, and allowed to flow into the bottle. 
They combine and produce a white crystalline solid, which quickly dis- 
appears when steam is admitted. Some water should also be poured 
down the open tube. The chemical changes are in part evident to the 
eye by the change of color which attends the conversion of red iSi O2 
into colorless NO, and vice versa. After the experiment has lasted ten 
or fifteen minutes, sufficient dilute acid will have collected in the bottle 
to respond to the tests given below. 

In practice it is found that loss of NO is constantly occur- 



100 ELEMENTS OF CHEMISTRY, 

ring, and so it is necessary to renew the nitric acid occasionally. 
The liquid on the floor of the leaden room is drawn off from 
time to time, and concentrated by boiling in lead pans until 
it becomes strong enough to attack the lead. The further 
concentration is conducted in glass or platinum vessels. 

Properties. Pure sulphuric acid is a colorless, oily liquid of 
a specific gravity of 1.848, boiling at about 640° F. (338° C). 
It is highly corrosive and poisonous. Exposed to the air, it 
absorbs water in considerable amounts. When added to water 
it produces heat, often sufficient to make the water boil, and 
the dilution of any considerable quantity must be performed 
with care. A diminution of bulk occurs when the acid and 
water are mixed. So great is the affinity of sulphuric acid 
for water that it will decompose many organic substances, ex- 
tracting the hydrogen and oxygen and leaving the carbon. 
The carbon so liberated will diffuse through the acid and give 
it a dark color. 

Commercial sulphuric acid is usually more or less brown, 
or even black, from the carbon set free from particles of dust, 
straw, etc. which accidentally fall into it. It always contains 
a small quantity of water — about one molecule to twelve of 
acid: 

H^O -f I2H2SO,. 

Its properties, boiling-point, etc. are similar to those of the 
pure acid. 

Nordhausen or Fuming Sulphuric Acid is the original oil 
of vitriol, so called because it was obtained by the distillation 
of green vitriol. It is substantially a solution of sulphur tri- 
oxide, SO3, in sulphuric acid. It is denser and even more 
corrosive than the common acid, and unites with water with 
great energy. It is used for dissolving indigo and for a few 
other purposes. When heated, the sulphur trioxide distils off, 
and the ordinary acid is left. 

The properties of sulphuric acid are greatly modified by 
dilution ; its corrosive and charring action may be entirely 



ELEMENTS OF CHEMISTRY. 101 

removed by adding much water. When such a dilute acid 
is boiled, it steadily loses water until the original degree of 
concentration is nearly or quite restored. The following ex- 
periments show the more important properties : 

Mix in a thin glass vessel equal volumes of strong sulphuric acid and 
water, and place upon the surface of the liquid a small capsule made 
of tin or copper foil and containing a small piece of phosphorus. 
The heat will be sufficient to ignite the phosphorus. If the quantities 
of water and acid be carefully measured, the amount of condensation 
may be observed. It will be about one-fifth. The dilute acid so ob- 
tained is useful for many experiments, and should be preserved. 

The milkiness produced in this mixture is due to the precipitation 
of lead sulphate formed from the pans in which the acid is concentrated. 
This body is soluble in the strong, but not in the dilute, acid. 

Place a few bits of straw, wood or common organic matter in some 
strong sulphuric acid. In the course of a few minutes the acid will be 
discolored by the carbon set free. This discoloration of the acid does 
not interfere with its ordinary uses. 

If any design be traced on white paper with the dilute acid obtained 
in a former experiment, and the paper then cautiously heated, the acid 
will slowly become more concentrated, and will finally char the paper 
completely, but only at the parts which have been touched by the 
original liquid. This experiment is made use of for the detection of 
small quantities of the free acid. 

The uses of sulphuric acid are very numerous. By its high 
affinity it is capable of expielling many other acids from com- 
bination. Nitric acid is made from nitrates, acetic acid from 
acetates, by its agency. Its affinity for water makes it a 
useful drying agent, especially for gases. Many organic 
bodies are peculiarly modified by treating wdth dilute sul- 
phuric acid, but these changes will be best understood when 
described under organic chemistry. 

Gen. Chem. Rel. The salts of sulphuric acid are called 
sulphates. Monads give, of course, two sulphates, acid and 
normal. Sodium gives us 

Acid sodium sulphate. Sodium sulphate. 

NaHSO^ Na,S04 

9* 



102 ELEMENTS OF CHEMISTRY, 

Dyads give but one sulphate. From barium we get BaSO^, 
barium sulphate. 

Most sulphates, except those of the calcium group, are 
freely soluble in water. 

Tests. The concentrated acid is easily recognized by its 
oiliness and charring action on organic matter. The dilute 
acid maybe made to produce this charring by evaporation, as 
described above. 

The general test for either the acid or any of its salts is the 
addition of a solution of some barium compound (barium 
nitrate, chloride or acetate) ; a white precipitate insoluble in 
water and dilute acids is at once formed, even if only a trace 
of the acid be present. The solution to be tested should be 
made acid with hydrochloric acid, to prevent carbonates, phos- 
phates, etc. being mistaken for sulj^huric acid. 

The commercial sulphuric acid contains several impurities. 
Of these the most important are arsenic and lead, which may 
be detected and removed by treating the diluted acid with 
hydrogen sulphide. 

Hyj)osulphurous acid, H2SO2, is produced by dissolving zinc 
in sulphurous acid. 

H2SO3 + Zn = ZnO + H2SO2. 

It is a powerful bleaching and reducing agent, and decomposes 
quickly. 

Thiosulphuric acid, H2S2O3, commonly but erroneously called 
hyposulphurous acid, has not been obtained in the free state. 
Calcium thiosulphate is formed in several manufacturing opera- 
tions, and sodium salt is much used in photography. The 
thiosulphates are powerful reducing agents. 

A sesquioxide of sulphur, S2O3, has been described, but is 
not important. 

The remainder of the sulphur acids have no particular in- 
terest, and will not be described. 



ELEMENTS OF CHEMISTRY, 103 

Compounds of Chlorine with Sulphur.— These have 
considerable theoretical and some practical interest, but will 
be only briefly mentioned. 

S2CI2 Sulphur chloride. 

SCI2 " dichloride. 

SCI, " tetrachloride (doubtful). 

The first two are liquids. S2CI2 is used as an agent in vul- 
canizing; rubber. 



SELENIUM, Se, 79.5. 

Selenium was discovered by Berzelius in 1817. 

Sources. It is found native and also in combination, form- 
ing selenides. It is rare. The method of preparation is not 
important. 

Properties. The physical properties of selenium resemble 
those of sulphur. It shows several allotropic forms. The prin- 
cipal interest attaching to it is that its power of conducting 
electricity is affected by light. Several forms of apparatus 
for the electrical transmission of iniages have been based 
upon this property. 

Gen. Chem. Rel. The compounds of selenium are anal- 
ogous to those of sulphur ; we have 



H,Se 


Hydrogen selenide. 


SeO^ 


Selenium dioxide. 


H^SeOs 


Selenous acid. 


HjSeO, 


Selenic " 



The last is capable of dissolving gold. 



104 ELEMENTS OF CHEMISTRY, 

TELLURIUM, Te, 129. 

Tellurium was discovered by Miiller in 1782. 

Sources. It is found native, and also in union with bis- 
muth, gold, etc. It is rare. The method of preparation is 
unimportant 

Properties. Tellurium has a metallic lustre and pinkish 
color. It fuses just below a red heat, and at a temperature 
somewhat higher boils. 

Its compounds are analogous to those of sulphur and sele- 
nium, and partly to those of the nitrogen group. 



Nitrogen Group. This includes boron, nitrogen, phos- 
phorus, arsenic, antimony and bismuth. They are neither 
strongly positive nor strongly negative, and act generally as 
triads, but also frequently as pentads, more rarely as monads. 
Among their compounds are found some of the most active 
mineral poisons known. Gold and vanadium may also be 
classed here. 

BORON, B, 11. 

Sources. Boron occurs only in combination; as boric 
acid in discharges of steam in the volcanic region of Italy, 
as sodium (or calcium) borate found in certain lakes in 
Thibet and upon the surface of the soil in western parts of 
the United States. Boron was first prepared by Davy in 
1807. 

Preparation. It is prepared by the action of potassium, 
sodium or aluminum on boric anhydride, B2O3. 

Properties. Boron obtained by the action of sodium or 
potassium is an amorphous, olive-green powder, insoluble in 
water and combustible. When obtained by the action of 
aluminum, it is, if pure, in brilliant crystals, closely resem- 



ELEMENTS OF CHEMISTRY. 105 

blino^ the diamond and next to it in hardness.- A form of 
boron analogous to graphite has been supposed to exist, but 
it is probably in an impure condition. 

Gen. Chem. Rel. Boron is a triad, and may be regarded 
OS a link between the carbon and nitrogen groups. Its com- 
pounds are not strictly analogous to those of any other ele- 
ment. 

Boric or Boracic Acid, H3BO3. This exists, as already 
mentioned, in the steam-jets discharged in some volcanic 
regions, and some of its salts occur as minerals. It can be 
prepared by dissolving borax in warm dilute sulphuric acid 
and allowing the solution to cool. Boric acid forms pearly 
scales of a bitter taste, soluble in water and alcohol and very 
feebly acid. Heated to 248^ F. (120° C), it forms metaboric 
acid, HBO2, and on still further heating it is converted into 
boric anhydride, B2O3, which fuses to a clear glass. When a 
solution of boric acid is boiled, some of the acid passes off in 
the steam. It forms salts called borates, many of which are 
irregular in composition. Boric acid is an antiseptic. 

Tests. Boric acid has a feeble action on litmus, and turns 
turmeric paper to a brown-red color. The best test is the 
bright green color imparted to flame. 

Exp. Shake a little boric acid with alcoliol, pour the solution into a 
flat dish and ignite. The outer cone of the flame will be tinged with 
green. 

Compounds of boron with nitrogen, chlorine, bromine and 
fluorine are known. 



NITROGEN, N, 14. 

Sources. Nitrogen constitutes about four-fifths of air, and 
occurs in many animal and vegetable tissues, especially in those 
performing the higher functions. It also occurs in the min- 
eral kingdom in the form of the sodium and potassium nitrates. 



106 ELE3IEJSJTS OF CHEMISTRY. 

The name means "producer of nitre." It was discovered by 
Eutherford in 1772. 

Preparation. The simplest method of preparing nitrogen 
is to burn out the oxygen from a limited amount of air. A 
substance of active combustible qualities like phosphorus or 
sodium is required for this purpose, as common combustibles, 
like coal, will be extinguished long before the oxygen is 
exhausted. 

Exp. A piece of phosphorus is placed on a small metal basin or 
block of wood floating upon water, and, being lighted, a bell-jar or 
wide-mouthed bottle is placed over it. The white fumes of phosphoric 
anhydride, P2O5, soon fill the jar, and are absorbed by the water, which 
rises to about one-third the height of the jar. The nitrogen so obtained 
is impure, but shows the properties of the gas. The pure gas may be 
made by the action of chlorine upon ammonia or by heating a mixture 
of potassium nitrite and ammonium chloride. 

Properties. Nitrogen is a gas without color, taste or 
smell. It does not, under ordinary conditions, burn or sup- 
port combustion. It is not poisonous, but will not support 
life. From this absence of striking properties no interesting 
experiments can be performed with it. At high temperature 
and under the influence of electric sparks it will enter in 
combination with a number of elements. In this way com- 
pounds may be formed with oxygen, boron, silicon, carbon, 
hydrogen, magnesium, etc. It is a little lighter than air, 47 
cubic inches weighing 14 grains ; 1 litre weighs 1.25 grms. 
It can be liquefied only by intense cold and pressure. 

Gen. Ohem. Rel. Nitrogen is generally a pentad ; some- 
times it acts as a triad, or even as a monad. Although in the 
free state it shows so little affinity, it forms by indirect means 
compounds with most of the elements. It is an essential 
ingredient of all the higher tissues of animals, and exists also 
in vegetable structures, but not so abundantly. In many 
compounds it appears to have weak afiinity, and these are 
apt to decompose. Most of the powerful explosives now in 



ELEMi:NTS OF CHEMISTRY, 107 

use — gun-cotton and nitro-glycerine, for instance — owe their 
qualities partly to the nitrogen present. 

Tests. Free nitrogen is recognized by its chemical indif- 
ference. In combination it is usually detected by being con- 
verted into ammonia by the action of alkalies. 

Air. The atmosphere is an intimate mixture of about four 
volumes of nitrogen with one volume of oxygen. It sur- 
rounds the earth like a shell or casing, and extends upward 
to a height which has been variously estimated at from 45 to 
200 miles. It is known not to be a compound by several 
tests, among which are — 

1st. It turns brown an alkaline solution of pyrogallin, and 
reddens nitric oxide, characters which belong only to free 
oxygen. 

2d. Air dissolved in water has its nitrogen and oxygen in 
a proportion different from that in undissolved air. A chem- 
ical compound would have the same comjDosition in both 
cases. 

3d. The composition is not constant nor in exact propor- 
tions, either by weight or volume, though approaching very 
closely the formula N4O. 

The fact that this mixture of gases varies so little in differ- 
ent places and under different circumstances is due to an 
action called diffusion, which is seen in all gases, in nearly 
all liquids, and would probably be noticed in some solids if 
high pressures should be used. All gases mingle with one 
another, so that sooner or later they produce a uniform mix- 
ture in spite of the influence of gravity. The rate of mixture 
depends on the density of the gas. It is expressed mathe- 
matically by saying that the rate of diffusion is inversely pro- 
portional to the square root of the densities. Suppose two 
gases have densities of 1 and 16 respectively ; the square root 
of the numbers will be 1 and 4, and then by inversion we 




108 ELEMENTS OF CHEMISTRY. 

find that the lighter gas will diffuse with four times the rapid- 
ity of the heavier. 

Exp, If we place a wide-mouthed bottle filled with coal 
gas over a similar one filled with air, as shown in the cut, 
the two gases will after a short time mix perfectly, and on 
applying a light an explosion will result. The bottles should 
have pretty wide mouths, or the explosion might be danger- 
ous. The rapidity Avith which the odor of coal gas pene- 
trates through a room when a leak in a pipe occurs is an 
instance of diffusion. If the gas were to obey the usual laws 
of gravity, it would rise to the ceiling, but it really penetrates 
to all parts almost the same as if it were escaping into an 
empty space. In the same way, although nitrogen has a 
density of 14 and oxygen of 16, they do not form separate 
layers, but are uniformly and permanently mingled. 

Ordinary air contains small quantities of other bodies 
besides nitrogen and oxygen. It always contains water, 
carbonic acid and ammonia ; frequently compounds of nitro- 
gen and oxygen, and also ozone. Besides these we have dust 
and the ]3roducts of animal and vegetable decomposition. 
The study of impurities of air has received much attention 
of late years, especially in view of the theory that many dis- 
eases are due to living organisms or germs which exist in the 
air. For these investigations the microscope has been neces- 
sary. 

The approximate composition of air was first demonstrated 
by Lavoisier in 1777. 

The accurate analysis varies somewhat ; the following may 
be taken as a fair average : 

Oxygen, 20.61 

Nitrogen, 77.95 

Carbon dioxide, .04 

Water, 1.40 

Traces of ammonia, nitric acid and marsh gas (CH^), and, in 
towns, sulphur compounds. 

The uniformity of the composition of air is assisted by the 



ELEMENTS OF CHEMISTRY. 109 

winds and currents which are continually agitating it. Its 
chemical properties are those of oxygen in a much diminished 
degree, on account of the dilution with nitrogen. It was for- 
merly taken as a standard for the specific gravity of gases, 
but hydrogen is now preferred. 100 cubic inches weigh 30.93 
grains; 1 litre weighs 1.29 grammes; 13 cubic feet weigh 
about 1 lb. At the level of the sea the pressure is, ordinarily, 
about 15 lbs., and will sustain a column of mercury 760 milli- 
metres, or 30 inches, in height. Water in its natural condition 
always contains some air in solution. 

The capacity of air for holding moisture increases rapidly 
as the temperature rises. The dryness or dampness of the 
atmosphere is not due to the actual quantity of moisture in it, 
but to the amount in proportion to what the air can take up. 
A cubic foot of air at 30"^ F. can absorb about 2 grains of 
water ; if it contains a grain and three-quarters, it will there- 
fore be nearly saturated and seem damp ; if the temperature 
rise to 80° F., the capacity for moisture will rise to 11 grains, 
and under these conditions it would seem dry if it held three 
grains of moisture, because, although the amount of moisture 
is nearly doubled, its capacity for moisture has increased over 
five times. The nearness of air to saturation is called the 
RELATIVE HUMIDITY. Air Saturated with water has a rel- 
ative humidity of 100 ; if half saturated, the relative hu- 
midity is 50, and so on. AVhen tiie temperature falls the 
moisture separates to a greater or less extent, and we have 
fog, rain or dew, and if the temperature gets below the freez- 
ing-point, we have snow or frost. 

Changes produced in the Atmosphere. — The changes 
which affect the chemical composition of the air are important. 
The respiration of animals and the processes of combustion 
are continually removing oxygen and introducing water, car- 
bonic acid and more or less organic matter. The decay of 
animal and vegetable substances introduces various gases, 
especially ammonia and hydrogen sulphide ; and the sulphur 

10 



110 ELEMENTS OF CHEMISTRY, 

of coal and coal gas furnishes sulphurous and sulphuric acid. 
The dust which is always floating in the air" contains a great 
variety of substances living and dead, and varies with the 
locality. The continued removal of oxygen is counterbal- 
anced by the respiration of plants, which, under the influence 
of light, decompose the carbonic acid, retaining the carbon 
and giving off the oxygen, especially at the under surface of 
the leaves. In this way the two great divisions of organic 
nature sustain each other. This fact is well shown in the con- 
struction of the ordinary aquarium, in which animal and plant 
life are maintained for a long time without renewal of the 
water. The nitrogen of the atmosphere is very little aflected. 
The ammonia and other gases are gradually oxidized or ab- 
sorbed by the soil and plants and washed out by the rains. 
The organic matter also oxidizes, and ozone is supposed to be 
especially active in this respect. 

Ventilation. — When animals are compelled to breathe air 
in a closed space, it becomes, sooner or later, by the removal 
of oxygen, incapable of supporting their life, and by the in- 
troduction of organic matter it becomes an active agent of 
disease. As all buildings interfere with the free circulation 
of the air, the problem of ventilation or proper renewal of the 
air is a very important one. The products of respiration and 
combustion are usually lighter, because warmer, than the air 
around, and tend to rise,*and the simplest systems of ventila- 
tion take advantage of this fact by arrangements which allow 
the foul air to escape at the top of the room and fresh air to 
enter at the bottom. Unfortunately, walls and windows are 
usually cold ; they chill this foul air and interfere seriously 
with its upward movement. Practically, good ventilation 
cannot be accomplished without some active mechanical as- 
sistance, such as a fan-blower or the draft of a chimney. 

Ammonia Gas, Amine, NH3. This substance has been 
known in some forms from a remote period. The name is 
derived from the temple of Jupiter Amnion in the Libyan 



ELEMENTS OF CHEMISTRY. 



Ill 



desert, which was a point at which the materials for making 
one of its compounds were collected. Ammonia exists in the 
air in very small quantities. It is given off in the decompo- 
sition of organic matter, especially animal remains, and was 
originally derived from refuse of this kind. It is also pro- 
duced by the action of hydrogen on nitric acid. The great 
source at the present time is the water which has been used 
for washing the common illuminating gas. The distillation 
of coal produces considerable ammonia, and this is removed 
by passing the gas through water. The so-called ammoniacal 
liquor is neutralized with an acid, and the resulting compound 
properly purified. Ordinarily, hydrochloric acid is used, and 
the reaction is ISTHs + HCl = NH^Cl. For the preparation 
of ammonia some compound containing it is decomposed by 
an alkali. The usual method is by treating a mixture of am- 
monium chloride, NH4CI, with lime ; the reaction is 

2NH,C1 + CaO = 2NH3 + H^O + CaCL. 

By passing the gas over dry lime the water is absorbed and 
the pure NH3 is collected. 

Ammonia is a colorless gas of a pungent odor. It is ab- 
sorbed by water in large amounts, one pint absorbing 700 
pints of gas and increasing fifty per cent, in volume. This 
solution exhibits most of the properties of the gas, and is 
much used under the name of aqua ammonite or solution of 
ammonia. 

Exp. The affinity of ammonia for water may be 
easily shown by filling a flask with the gas and in- 
verting it in water. The ammonia will be rapidly 
absorbed, and the water will rise into the vacuum 
thus produced. 

Ammonia burns, but not easily. It is lighter 
than air. 1 litre weighs 0.76 grm. ; 47 cubic 
inches weigh 8.5 grains. It contains one vol- 
ume of N and three volumes of H, condensed 
to two volumes. At a temperature of — iO^ F. 




112 ELEMENTS OF CHEMISTRY. 

( — 40° C), or under a pressure of 100 lbs. to the square inch, 
it condenses to a colorless liquid. This liquid of course evap- 
orates rapidly when the pressure is removed, and produces 
great cold, which fact has been made use of in machines for 
making ice. 

Gen. Chem. Rel. The important property of ammonia is 
the strongly alkaline and basic power of its solution in water. 
This solution has chemical characters so much like those of 
potassa and soda that it is now generally believed that the 
ammonia and water have formed a compound ^vhich is analo- 
gous to the alkalies. Long before the composition of the solu- 
tion was understood it had received the name of volatile alkali, 
to indicate its resemblance to potassa and soda, which were 
called fixed alkalies. Berzelius was the first to suggest that 
the compounds produced by ammonia were formed in the 
same manner as those of potassium and sodium, these ele- 
ments being represented by the radicle., NH^. In this way 
NHs + HCl would produce NH4CI ; NH3 + H.O would pro- 
duce NH4HO. NH4 is called ammonium ; its atomicity is 
monad ; it combines with one atom of chlorine and replaces 
the hydrogen of acids. 

The following formulse show the comparison between the 
salts of potassium and those of ammonium : 

KCl Potassium chloride. 

NH4CI Ammonium chloride. 

K2SO4 Potassium sulphate. 

(^114)2804 Ammonium sulphate. 

KNO3 Potassium nitrate. 

NHiNOa Ammonium nitrate. 

KHO Potassium hydrate. 

NH4HO Ammonium hydrate. 

As the expression NH4 makes some confusion in formulae, 
it is convenient to use the symbol Am ; ammonium chloride 
will thus be AmCl ; ammonium sulphate, AmaSO^. The am- 



ELEMENTS OF CHEMISTRY. 113 

monium theory received considerable support when proposed 
from the following experiment: 

If a pi6ce of sodium be put on the surface of some mercury, and a 
drop of water added cautiously, an alloy called sodium amalgam will 
be formed. If this be dropped into a strong solution of ammonium 
chloride, a remarkable increase in bulk of the amalgam will take 
place. It was at first supposed that a compound had been formed 
between the mercury and NH^ by the following reaction: 

Sodium amalgam. Ammonium amalgam. 

HgNa2 + 2NH,Cl = 2NaCl + (NHj2Hg. 

The property of forming an amalgam with mercury was regarded as 
proof of the existence of NH^. Subsequent research has shown that the 
supposed ammonium amalgam is nothing but mercury inflated with gas- 
bubbles. The mass rapidly diminishes in bulk, giving off a mixture 
ofNHsandH. 

Although this experiment is no longer of any weight, the 
theory is generally accepted, because it greatly simplifies the 
study of the ammonium compounds. 

Ammonium, NH^, and ammonium oxide, (^"114)^0, have 
not been obtained in a form convenient for study. 

Ammonium Hydrate, NHJIO, has already been men- 
tioned as the supposed result of the solution of ammonia gas 
in water. It is a clear liquid, lighter than ^vater, corrosive 
and powerfully alkaline and pungent. 

Ammonmm Carbonate^ (NH4)2C03, is made on the large 
scale by heating ammonium chloride with chalk. The theo- 
retical reaction would be 

2 AmCl + CaCOs = CaCl^ + Am.COs. 

The AmaCOs, however, decomposes into AmaO, which escapes 
and leaves 2Am2C03 + CO2, ammonium anhydro-carbonate 
(see page 44), often called sesquicarbonate, or smelling-salt. 
It is a white body, soluble in water, and smelling strongly of 
ammonia. By exposure to air it is converted into acid car- 
bonate, AmHCOo. 
10 ^i^ 



114 ELEMENTS OF CHEMISTRY. 

Ammonium Nitrate, AmlSTOs, is made by saturating nitric 
acid with ammonia. It is a white solid, very soluble in water. 
Its chief use is for making nitrous oxide. 

Ammonium Sulphate, Am2S04, is obtained by boiling gas- 
liquor and passing the vapors into sulphuric acid. It is used 
as a fertilizer and in the manufacture of alum. 

Ammonium Phosphates. Of these the most important is 
microcosmic salt, AmNaHPOi. It is used in blowpipe analy- 
ses. Various ammonium phosphates exist in manures, and 
are valuable fertilizers. 

Ammonium Chloride, Sal Ammoniac, AmCl, is prepared 
as described on page 111. It is a white solid, crystallizing in 
cubes, and is very soluble in water. It volatilizes without 
fusing, and is apparently decomposed into HCl and NH3. 
It has many uses in the arts, in medicine and in analytical 
chemistry. 

Ammonium Bromide and Ammonium Iodide are used in 
photography and medicine. 

Tests. Any ammonium compound may be detected by 
heating it with potassium or sodium hydrates or slaked lime. 
Ammonia gas is quickly evolved, and may be recognized by 
its odor, alkaline reaction and the white cloud of NH4CI pro- 
duced when it comes in contact wdth vapors of hydrochloric 
acid. Ammonium compounds give the precipitates with plat- 
inum chloride and tartaric acid similar to those yielded by 
potassium. The most delicate test for ammonium is Nessler's 
reagent, a solution made by mixing HgCla, KI and KHO or 
ISTaHO. The liquid so formed produces, with very minute 
quantities of ammonia, a yellow color or a yellowish-red pre- 
cipitate. One patt of ammonia in fifty million parts of water 
can be easily recognized. 

Nitrogen Oxides. Five compounds of nitrogen and oxy- 
gen have been obtained : 



ELEMENTS OF CHEMISTRY, 115 

N2O Nitrous oxide, laughing gas. 

NO Nitric oxide (often written N2O2). 

N2O3 Nitrous anhydride. 

NO2 Nitrogen peroxide (often written N2O4). 

N2O5 Nitric anhydride. 

The system of names given to these compounds is in some 
confusion, partly because they were formerly assigned a some- 
what different composition, and partly because some writers 
double the formulae. Thus, NO is often written N2O2, and 
called nitrogen dioxide, because of the O2 present. NO2 is 
written N2O4, and called nitrogen tetroxide. The names and 
formulae given above are in the main preferable. 

Nitrogen and oxygen combine to a limited extent under the 
influence of high temperature, especially of the electric spark, 
generally producing one of the higher oxides. The common 
source of the compounds is decomposition of nitrates, espe- 
cially nitric acid. 

Nitric Acid, Aqua fortis, HNO3. This body has been 
known in the free state for a long time, and two of its salts, 
KNO3 and NaNOs, are found in large amounts as minerals ; 
the former in India, the latter in Peru and Chili. The usual 
method of obtaining the acid is by the action of strong sul- 
phuric acid upon the nitrates. For commercial purposes 
sodium nitrate is used, being the cheaper salt. The reaction 
is 

2NaN03 + H2SO4 = Na2S0, + 2HNO3. 

The complete action requires a high temperature. For a lab- 
oratory experiment it is preferable to use less sodium nitrate, 
and the reaction will be — 

NaN03 + H2SO, = NaHSO, + HNO3. 

Exp. Mix in a retort equal weights of powdered sodium nitrate and 
sulphuric acid ; connect the retort with a receiver set in cold water, and 
apply to the mixture a gentle heat. The nitric acid distils over, and 
will condense in the receiver as a slightly yellow fuming liquid. The 



116 ELEMENTS OF CHEMISTRY. 

experiment is best performed in a well-ventilated place. No corks or 
gum tubing should be used in connecting the apparatus. 

Nitric acid thus obtained has the composition HlSTOg, but it 
is difficult to prevent it absorbing water, and it is generally 
yellow from slight decomposition ; w^hen quite pure it is color- 
less. The ordinary acid has the composition 2H2O + HNO3. 
It is a strongly acid liquid, decomposing in the light, highly 
corrosive and poisonous, and of active chemical qualities. Its 
special value in chemistry is its high oxidizing pow^er. One- 
half the oxygen wdiich it contains is available, and is given 
up to a great variety of substances. Some variation occurs 
in the action, but the effect is in most cases represented thus : 

2HNO3 decomposes into H,0 + 2X0 + O3. 

The O3 is the available oxygen ; the NO y>dll be hereafter 
described as nitric oxide, and its escape is one of the most 
characteristic evidences of the action of the acid. With some 
bodies of low affinity the acid acts simply by exchanging its 
hydrogen for the other substance. Thus : 

Zn + 2HNO3 = ZnCNOs)^ + H,. 

The evolved hydrogen, however, attacks another portion of 
nitric acid and forms ammonia. This effect is made use of in 
the detection and estimation of nitrates, especially in drinking- 
w^ater. The action can be easily observed by making a mix- 
ture of zinc and dilute sulphuric acid, and adding nitric acid. 
The hydrogen, which is copiously evolved when the sulphuric 
acid alone is present, slowly diminishes upon adding the nitric 
acid, and may even cease to come off. After a time a perceptible 
amount of ammonia will be formed. The action is even better 
produced when we dissolve aluminum foil in a solution of 
caustic alkali mixed with a small quantity of a nitrate. 

With bodies w^hich do not easily displace hydrogen the ac- 
tion of nitric acid is highly characteristic. It exerts the spe- 
cial oxidizing effect referred to above. Two molecules of the 
acid give up three of oxygen, and form oxides which may or 



ELEMENTS OF CHEMISTRY. 117 

may not be basic accordii^g to the nature of the body or the 
quantity of the oxygen taken. If basic oxides are formed, 
tliey will unite with another portion of the acid to form 
nitrates. We may suppose, in the case of copper, the fol- 
lowing to take place: 

Cu3 + 2HXO3 = 3CuO + H,0 + 2X0. 

The XO escapes as a gas ; the CuO immediately acts upon 
and neutralizes six additional molecules of nitric acid, 

3CuO + 6HXO3 = 3CuX A + 3H A 

The complete reaction, therefore, is 

3Cu + 8HXO3 = 3Cu(X03)2 + 4H,0 + 2X0. 

Tin gives the following : 

Sn3 + 4HXO3 = 3SnO, + 2H,0 ^- 4X0. 

SnO.2, not being basic, does not combine with any nitric acid. 
Many organic bodies are oxidized in this manner, and are 
often colored yellow by the action. 

Another action of nitric acid is its power of forming sub- 
stitution compounds. The study of these bodies belongs to 
organic chemistry, but a single illustrative reaction n:iay be 
here given. When benzene, CeHg, is treated with strong nitric 
acid, one atom of hydrogen is removed and one molecule of 
XO2 put in its place. We have 

CeHe + HXO3 - CeH5(X0,) + H,0, 

and the body so formed is called Nitrobenzene. 

A mixture of nitric and sulphuric acids is often used for 
such effects. 

Very strong nitric acid fails to act upon some substances 
which are readily attacked by the more dilute forms. 

Tests. The strong acid may be recognized by its odor and 
its power of producing yellow stains on organic matter. 

Free nitric acid produces the following marked reactions : 



118 ELEMENTS OF CHEMISTRY. 

Morphia and brucia are colored red ; copper is dissolved, 
with the production of red fumes of NO2. When the acid is 
in combination a few drops of sulphuric acid should be added. 
As all normal nitrates are soluble in water, no precipitation 
test for the acid is know^n. 

Nitrous Oxide, N.^O, laughing gas, often called nitrogen 
monoxide. This body w^as discovered by Priestley in 1776. 
It is best obtained from ammonium nitrate, wdiich, when care- 
fully heated, decomposes completely into nitrous oxide and 
steam, 

NH,N03 = N,0 + 2KA 

Nitrous oxide is a colorless, odorless gas, wdth a somew^hat 
sweetish taste. It can be breathed for a short time w^ithout 
injury, and produces a transient intoxication. When the gas 
is inhaled in quantity, a short insensibility is produced, during 
which brief operations, such as teeth extractions and opening 
of abscesses, may be performed. It supports the burning of 
ordinary combustibles almost as well as oxygen. It is some- 
what soluble in w^ater. At a pressure of fifty atmospheres it 
becomes a colorless liquid, and is now sold in this form com- 
pressed in strong metal cylinders. 

Nitric Oxide, NO, often called nitrogen dioxide and writ- 
ten N2O2. This gas is the usual product of the action of nitric 
acid as an oxidizer. It is conveniently prepared by the action 
of nitric acid on copper. The reaction is 

Cus + 8HN0;, = SCuiNOs)^ + 4H,0 + 2N0. 

Some N2O is often produced in this experiment. 

NO is a colorless gas, very difficult to reduce to the liquid 
form. Its most marked property is that as soon as it is 
brought in contact w-ith oxygen, it instantly absorbs one 
atom, becoming NOo and turning brownish-red. . This body, 
NO2, parts wdth the second atom of oxygen rather easily, and 
leaves the NO ready to absorb more oxygen. In consequence 
of this property nitric oxide is used as a sort of carrier of 



ELEMENTS OF CHEMISTRY. 119 

oxygen, particularly in the manufacture of sulphuric acid. 
In the ordinary method of making nitric oxide a portion is 
always converted into NOj ; this can be removed by collect- 
ing the gas over water, which absorbs the NO2. 

Nitrogen Peroxide, or Nitric Peroxide, NO2. This 
body has various names, owing to uncertainty in its chemical 
relations. It has been called nitrogen tetroxide (being written 
N2O4 by some chemists) and hyponitric acid, and also by other 
less common names. The proper name would be nitrogen di- 
oxide, to correspond to the formula NO2, but as this name has, 
unfortunately and very unwisely, been given by some writers 
to nitric oxide, it is probable that the rather unsatisfactory 
name, nitric peroxide, will have to be retained. 

IvF02 is a brownish-red gas, of which the color depends 
somewhat on the temperature; at about 14° F. ( — 10° C.) 
it condenses to a liquid. It is readily absorbed by water, 
which decomposes it, producing various compounds accord- 
ing to the proportions used. 

The following experiments illustrate the general relation 
of the nitrogen oxides : 

1. Mix in a glass bottle or retort some copper turnings with moder- 
ately strong nitric acid. The evolved gas will have a red color, and 
consist of n, variable mixture of N2O, /^^ 

NO and NO2. Pass the gas into a jar JL^^ 

of water inverted over the pneumatic 

trough, and it will be found that a 

colorless gas is collected. This is 

because the KO2 is absorbed by the 

water. 

2. Allow a few bubbles of air to 
pass up into the jar; a red color is at once produced, which soon dis- 
appears, the water rising slightly in the jar. This effect is due to the 
conversion of the NO into NO2, and the subsequent absorption of the 
latter by the water. The experiment may be repeated until all the 
NO is oxidized, and the residual gas is a mixture of N2O and N. 

3. If pure nitric oxygen and pure oxygen be used in this experiment, 



120 ELEMENTS OF CHEMISTRY. 

the relation bv volume will be easily shown. Two pints of nitric oxide 
contain one pint of N and one of O. If mixed with an additional pint 
of oxygen, NO2 will be formed, and complete condensation will ensue. 

Nitrous anhydride, N2O3, and nitric anhydride, N2O5, are 
unimportant, as is also nitrous acid, HIS 0^ ; but a few of the 
nitrites are of importance. Ammonium nitrite occurs in rain- 
Avater, and other nitrites are found in river- and v/ell-water. 
They act both as oxidizing and reducing agents. 



PHOSPHORUS, P, 31. 

Sources. Phosphorus occurs principally as calcium phos- 
j)hate, which exists in bones and teeth, in many minerals and 
in soils. Various phosphates also exist in the fluids of the 
animal body. It was discovered by Brandt in 1669. The 
name means " carrier of light." 

Preparation. Phosphorus is prepared from bones, which 
contain from one-third to two-thirds their weight of calcium 
phosphate. The bones are deprived of their animal matter, 
and the hone-ash thus left is treated with sulphuric acid, by 
wdiich a soluble acid calcium phosphate is formed and much 
calcium sulphate is deposited. The liquid is then concentrated, 
mixed with charcoal and sand and heated. Calcium silicate 
is produced, the charcoal takes the oxygen, and the phosphorus 
distils over. The reactions are complicated ; the following is 
to be considered as merely an indication of the change, and 
not the exact formula: 

Bone ash. 

CasCPO J2 + 2H2SO, = 2CaS0, + CaH,(PO02. 

Acid cal. phosph. Sand. 

CaH,(P0,)2 + SiO, + C5 = CaSiOs + 2H,0 + 5C0 + P^. 

Other methods of manufacture are known, but need not be 



ELEMENTS OF CHEMISTRY. 121 

described. The distilled pliospliorus is collected in water and 
cast in sticks. 

• Properties. Phosphorus when freshly prepared is a color- 
less, almost transparent solid, soft as wax ; when kept for some 
time, especially in the light, it becomes brownish, opaque and 
harder. It takes fire easily, and is usually kept under v/ater. 
It burns with a bright flame, producing white clouds of phos- 
phoric anhydride, P2O5. Exposed to the air at low tempera- 
ture, it can still undergo a slow combustion, producing P2O3 ; 
it is then luminous in the dark. It is insoluble in w^ater, but 
dissolves in oils and in carbon disulphide. It is extremely 
poisonous, death having occurred from much less than J grain. 
Phosphorus melts at 111^ F. (43^ C), and boils at 550^ F. 
(288° C), producing a vapor which according to analogy 
should be 31 times as heavy as hydrogen, but is really 62 
times as heavy. By keeping it at a temperature of 450° F. 
(232° C.) for days in a closed vessel, phosphorus is converted 
into the 

Amorphous or red phos]pliorus, an allotropic form which is 
red, insoluble in carbon disulphide, difficult to burn, non-poi- 
sonous, and show^s many other minor differences. Its composi- 
tion is the same. This change is also produced by adding a 
small quantity of iodine to common phosphorus. 

The uses of the element in matches and as a medicinal sub- 
stance are well knov;n. 

In all experiments with it great care must be taken, as it is 
easily inflamed and produces one of the most severe forms of 
burns know^n. It should be handled wdth a pair of forceps 
and cut or divided only under w^ater. 

Gen. Chem. Rel. Phosphorus acts as a triad or pentad ; 
its affinities in the free state are very high. It is a powerful 
reducing agent. Its important properties are shown in experi- 
ments given in the description of other elements. 

The formation of tlie amorphous variety may be noticed by adding a 
few grains of iodine to a small fragment of common phosphorus. 
Jl 



122 ELEMENTS OF CHEMISTRY. 

Tests. Phosphorus in the free state is easily recognized. 
In very minute quantity it is detected by its luminosity when 
distilled in a dark room. 

Hydrogen Phosphide, PH3, Phosphine. This body is 
formed under conditions analogous to those which produce 
ammonia ; that is, when its elements are brought together in 
the nascent state (page 37). When a solution of caustic 
alkali is boiled wdth phosj)horus, water is decomposed and hy- 
drogen phosphide is formed. 

Exp. Pieces of phosphorus are put into a small retort, which is then 
nearly filled with a strong solution of caustic soda, and arranged so that 
the end of the tube can be quickly put below the surface of water in a 
basin. The retort is heated carefully, and when the mixture boils the 
hydrogen phosphide will come oiT. The end of the retort should then 
be put below the water. The gas passes through the water, and burns 
on reaching the air. The experiment requires care, and should be per- 
formed only by those who have some acquaintance with such manip- 
ulations. When the action is over it is best to simply leave the appa- 
ratus to itself, as a slight explosion generally occurs. 

The reaction is 

SNaHO + 3H,0 + P^ = 3NaH,P0, + PH3. 

NaHaPOs is sodium hypophosphite. Hydrogen phosphide 
is a colorless gas of a disagreeable odor. As ordinarily made 
it is spontaneously inflammable, but this is due to the pres- 
ence of a small quantity of the vapor of a liquid phosphide, 
PH2. If this latter be removed by passing the fresh gas 
through a tube placed in a freezing apparatus, the power of 
inflaming spontaneously is lost. A solid phosphide, appa- 
rently P2H, is also known. 

The inflammable gas can also be prepared by the action of 
water on calcium phosphide. 

Hydrogen phosphide has no alkaline properties, but forms 
many compounds analogous to those formed by ammonia. 

Compounds of Phosphorus with Oxygen.— Only two 
compounds are definitely knowm. These are : 



ELEMENTS OF CHEMISTRY. 123 

P2O3 Phosphorous anhydride. 

P2O5 Phosphoric anhydride. 

Phosphorous Anhydride, PA, is produced by the slow 
oxidation of phos^^horus. When this takes place in ordinary 
air, water is absorbed and phosphorous acid, H3PO3, is formed. 
This is a powerful reducing agent, but is not an important 
body. 

Phosphoric Anhydride, P2O5. This is the product of the 
active combustion of phosphorus. It is easily produced by 
burning phosphorus in the air. It forms white, snow-like 
fumes, which rapidly absorb water. 

Exp. Ignite a small piece of phosphorus on a common plate and 
cover it with a jar. The white clouds of P2O5 soon begin to settle on 
the plate, and when the combustion is finished throw a few drops of 
water on the white deposit ; a hissing sound will be heard, due to the 
energetic union of the anhydride with the water. 

Phosphoric anhydride is a white, snow-like solid, having a 
very high affinity for water. It is capable of uniting with 
water in at least three proportions, forming different bodies ; 
very few anhydrides show this power, and consequently the 
chemistry of these phosphoric acids is more than ordinarily 
complicated. When the anhydride is mixed with water as in 
the above experiment, it combines with one molecule of water 
and forms IIPO3. If, however, the acid be obtained from 
any of the phosphates found in nature, it has the formula 
HaPO^; and this can be produced from the anhydride by 
heating with three molecules of water. An intermediate 
acid, H4P2O7, is also known. The relation between these 
different forms is shown in the following equations : 

P2O5 + Tl.O ==: 2HPO3 Metaphosphoric acid. 

P2O5 + 2H,0 = H.P.O; Pyrophosphoric " 

P2O5 + 3H2O =r 2IT3PO, Orthophosphoric " 

The last acid is the one that yields all the natural phos- 
phates ; the syllable '' ortho " means " regular,'^ and signifies 



124 ELEMENTS OF CHEMISTRY. 

"pyro" means "fire," and signifies that the second acid, 
H4P2O7, is obtained by the action of heat upon some of the 
natural phosphates. By the further action of heat the meta- 
phosphoric is obtained. 

Properties and Gen. Ohem. Rel. of the phosphoric 
acids. Metaphosphoric and pyrophosphoric acids are of 
comparative unimportance. They are artificial products of 
the laboratory. The first mentioned is distinguished by a 
power of coagulating albumen. It is to be particularly 
noticed that although the three phosphoric acids differ in 
oxygen, the termination "ic" is not changed. This is 
because they are all formed from the same anhydride; the 
diflTerence in oxygen is due to the amount of water. The 
number of salts formed by each acid is in proportion to the 
number of molecules of w^ater which it has taken up. 

Metaphosphoric Acid, produced by adding one molecule 
of water, gives one series of salts : 

NaPOs Sodium metaphosphate. 

Ca(P03)2 Calcium 

Pyrophosphoric Acid, produced by adding two molecules 
of water, gives two series of salts, acid and normal : 

Na2H2P207 Acid sodium pyrophosphate. 

Na^P^Or Sodium 

Orthophosphoric Acid, produced by adding three mole- 
cules of w^ater, gives three series of salts, di-acid, acid and 
normal. 

NaHsPO^ Di-acid sodium orthophosphate. 

Na^HPO, Acid 

NaaPO^ Sodium orthophosphate. 

The phosphates of the potassium group are soluble in 
water. Almost all others are insoluble in vvater, but sol- 
uble in acids. 

Tests. The detection of metaphosphoric and pyrophos- 
phoric acids is not often required, but orthophosphoric acid 



ELEMENTS OF CHEMISTRY, 125 

is a body very often encountered in analysis. Silver nitrate 
produces with it a yellow precipitate soluble in ammonia. 
A mixture of magnesium sulphate, ammonia and ammonium 
chloride gives a white precipitate soluble in acids. A solu- 
tion of ammonium molybdate in nitric acid gives a bright 
yellow precipitate insoluble in acid. This is a very delicate 
test. 

The compounds of phosphorus with otlier elements are of limited 
importance. With sulphur it gives a variety of combinations. The 
action between the two elements may be shown by igniting a piece of 
phosphorus, placed in the midst of a mass of finely-powdered sulphur. 
A quick combustion, producing a large flame, at once occurs. The 
phosphorus sulphide first formed is probably quickly consumed. 

Two phosphorus chlorides are known, PCI3 and PCI5. 
They have been much used in researches in organic chem- 
istry. Compounds with bromine and iodine are also known. 



ARSENIC, As, 75. 

Sources. Arsenic occurs in the free state and as sul- 
phide, also in combination, especially with nickel, cobalt and 
iron. It is rather abundant, and exists in small amounts in 
many minerals. 

Preparation. Arsenic is prepared by deoxidizing ar- 
senous anhydride by charcoal, 

AsA + C3 = As2 + 3CO. 

It w^as first prepared by Brandt in 1733. 

Properties. Arsenic, when freshly prepared, is a steel- 
gray, brittle mass with a decided lustre. It tarnishes some- 
Avhat in the air, and passes into vapor at about 356^^ F. (180° 
C.) without fusing. The vapor has a density twice as great 
as analogy would require. Heated in contact with air, it 
oxidizes to arsenous anhydride, and develops a garlicky odor. 
It is not dissolved by any simple solvent. 
11* 



126 ' ELEMENTS OF CHEMISTRY. 

Gen. Chem. Rel. Arsenic is similar to nitrogen and phos- 
phorus in its chemical relations. 

Tests. These are given under arsenous anhydride. 

Arsenetted Hydrogen, Arsine, AsHs. This body is anal- 
ogous to ammonia, and, like it, is produced when its elements 
are brought together in the nascent state. Its formation is one 
of the most delicate tests for arsenic. The usual method of 
preparation is to liberate hydrogen in a solution of arsenous 
anhydride. It is a combustible gas of disagreeable odor and 
excessively poisonous. 

A solid arsenous hydride of uncertain composition is kno^Yn. 
Compounds of Arsenic with Oxygen.— These are two : 

AS2O3 Arsenous oxide or anhydride. 

AS2O5 Arsenic " " 

Arsenous Anhydride, Arsenous Oxide, White Arsenic, 

AS2O3. This is the substance generally called arsenic. It is 
obtained by roasting arsenical ores in a current of air, and 
presents itself in commerce in two varieties : 

(a) The vitreous form, transparent and colorless at first, 
but afterward becoming yellowish and porcelain-like; 

(b) A pulverulent form, which is distinctly crystalline. 

Properties. Arsenous anhydride is a white solid, odorless 
and tasteless, and dissolving with difficulty and only in small 
amounts in cold water ; the solution is feebly acid, and is sup- 
posed to contain arsenous acid, H3ASO3. Hot water is a more 
active solvent, but the amount dissolved is dependent on many 
conditions and variously stated by difierent observers. As a 
rough statement it may be said that a fluidounce of cold 
w^ater will dissolve about one grain, and the same amount of 
w^ater if kept for one hour at the boiling-point will take up 
about forty grains. In acid and alkaline solutions it dissolves 
much more readily. Heated to 380° F. (193° C), the solid 
passes into vapor without fusing, and if allowed to condense 



ELEMENTS OF CHEMISTRY. 



127 




produces brilliant, transparent crystals. It is intensely poi- 
sonous in all its forms, two or three' grains being a fatal dose. 
Arsenous anhydride is used in making opaque white glass, in 
various solutions for preserving animal skins, and in the manu- 
facture of colors. Its frequent occurrence and poisonous quali- 
ties have made its properties and tests of great importance. 
The followmg is a brief summary of the methods used. 

' 1. Reduction Test. — This depends on the 

conversion of the arsenical compounds into 

the elementary arsenic. A small quantity of 

powdered white arsenic is mixed witli some 

dried potassium ferrocyanide and heated in a 

narrow glass tube. The elementary arsenic is 

set free, rises in vapor, and condenses on a cooler . 

portion of the tube, as a dark steel-gray but rather lustrous layer called 

the arsenical mirror. If this deposit be heated, it may be driven farther 

along the tube, and ayHI finally oxidize and produce the garlicky odor. 

2. Sublimation Test. — Arsenous oxide heated 
alone passes quickly into vapor, and by allowing 
this vapor to condense upon s^slighflyicarmed part 
of the tube fine crystals are formed. Under the 
microscope these crystals are seen to be octa- 
hedral ; that is, consist of eight triangular faces, 
though they are rarely completely formed. Very 
minute quantities of arsenic can be recognized 
by this test. 

3. Reinsch's Test. — This is the most valuable test, because it can be 
applied to impure mixtures, as the contents of a stomach. A small 
quantity of water is put into a wide test-tube or porcelain basin ; some 
hydrochloric acid is added ; a piece of clean copper is put in and the 
water brought to boiling. A few drops of a solution of arsenic are now 
added, and in a few seconds a rather dull steel-colored deposit of copper 
arsenide forms on tlie copper. When this deposit has become rath.er 
dense, the copper is taken out, dried with filter-paper, rolled up into small 
bulk and placed in the end of a small glass tube. Heat being applied, 
the arsenical deposit is oxidized and volatilized, forming octahedral 
crystals of arsenous anhydride. 

4. Marshes Test. — This depends on the power of nascent hydrogen to 
form AsHg. The hydrogen is obtained either by the action of sulphuric 
acid upon zinc or magnesium, of sodium amalgam on water, or by a 




128 ELE3IENTS OF CHEMISTRY, 

current of electricity. The test is very delicate, but requires great 
skill in its manipulation. The simplest method of performing it con- 
sists in mixing zinc and dilute sulphuric acid in a gas bottle, allowing 
the hydrogen to flow for some time, and then introducing a small quan- 
tity of arsenical solution. The arsine, AsHg, begins at once to come 
off; the flame of the hydrogen becomes livid and gives off fames of 
arsenic. If a cold porcelain plate be held in the flame, an arsenical 
soot will be deposited as a brown shining stain. If the tube which is 
conducting the current be heated, the gas will be decomposed and a 
similar stain formed within the tube. The stains may be identified as 
arsenic by the fact that they are — 

(a) easily volatile ; 

(6) soluble in a solution of bleaching-powder; 

(c) capable of producing octahedral crystals of AS2O3. 

Three tests, known as the liquid tests, are applicable only to pure 
solutions of arsenous anhydride. They are — 

1. Hydrogen sulphide produces a lemon-yellow precipitate of ar- 
senous sulphide, AS2S3. 

As,03 + 3H2S = As^Ss + 3H2O. 

A few drops of hydrochloric acid facilitate the action. 

2. Silver nitrate, made alkaline by ammonia, gives a yellow precipi- 
tate of silver arsenite. 

3. Copper sulphate, made alkaline by ammonia, gives a green pre- 
cipitate of copper arsenite. 

Arsenic Anhydride, AS2O5. This is produced by oxidiz- 
ing arsenous anhydride with nitric acid. It forms, with water, 
arsenic acid, H3ASO4, which is used as an oxidizing agent 
in the manufacture of aniline colors. This use has been sup- 
posed to account for the cases of skin irritation which have 
been occasionally observed to follow the wearing of fabrics 
dyed with these colors, but it is very doubtful if any arsenic 
remains in the manufactured article. 

Arsenic acid forms salts called arsenates. It is usually 
tested by first converting it into arsenous acid. Three forms 
of arsenic acid are known, corresponding to the three forms of 
phosphoric acid. 



ELEMENTS OF CHEMISTRY. 129 

Compounds of Arsenic and Sulphur.— Three of these 
are known : 

AS2S2 Arsenous disulphide, realgar. 

AS2S3 Arsenous sulphide, orpiment. 

AS2S5 Arsenic " 

Realgar is a brick-red solid, easily volatile. It is found as 
a mineral, and may also be produced artificially. It has little 
practical importance. 

Orpimenty King's yellow, is found as a mineral, and is easily 
produced artificially by the action of hydrogen sulphide upon 
arsenous anhydride. 

AS2O3 + 3H2S = As^Ss + 3H2O. 

It is a bright yellow solid, fusible and volatile, soluble in 
alkalies, but insoluble in water and dilute acids. It is often 
obtained in the process of testing for arsenic, and in the arts 
is used as a pigment. 

Arsenic sulphide is unimportant. 

Arsenic forms chlorides, bromides and iodides, but they 
need not be described. 



ANTIMONY, Sb, 122. 

Sources. Antimony occurs sometimes in the free state, 
but generally as sulphide, Sb2S3. It was discovered by Basil 
Valentine in the fifteenth century. It is also called Stibium, 

Preparation. By melting the roasted antimony sulphide 
wdth charcoal and sodium carbonate. The reaction is anal- 
ogous to that occurring in the preparation of arsenic. 

Properties. Antimony is bluish-white, brittle, generally 
highly crystalline and of brilliant lustre. It fuses at 842° F. 
(450"^ C), and volatilizes at a red heat. On cooling from 




130 ELEMENTS OF CHEMISTRY, 

the melted condition it expands somewhat, and some of its 
alloys retain this projDerty, for which reason, it is used in 
type-metal and other alloys which must take sharp casts. 
Like arsenic, it is not soluble in any simple solvent. 

Exp, Heat a piece of antimony 
about the size of a large shot on 
a piece of charcoal by means of 
the blow]3ipe, and when the mass 
is in perfect fusion drop it from 
a height of several feet upon a 
large sheet of paper. The glob- 
ule will splash and tlirow little 
globules in all directions, each of 
which leaves a train of antimony 
oxide. 

Gen. Chem. Rel. The chemical relations of antimony 
are much like those of arsenic, phosphorus and nitrogen, 
but, unlike them, it forms an oxide which is slightly basic. 

Tests. Antimony is detected by tests similar to those of 
arsenic. The distinctive differences are : 

1. The sublimate of free antimony cannot be obtained by 
the reduction test unless a very high temperature be used. 

2. The antimony oxide cannot be volatilized except by a 
high heat, and does not usually form octahedral crystals, but 
these have been obtained under certain conditions. 

3. The copper slip in Reinsch's test becomes covered with 
a bluish or violet deposit, which gives a sublimate only with 
great difficulty. 

4. In Marsh's test a much darker spot is obtained ; it is 
volatilized with difficulty, and not ' dissolved by a solution 
of bleaching-powder. 

5. The liquid tests give no result except with hydrogen 
sulphide, which produces an orange-red precipitate. 

Stibine, Antimonetted Hydrogen, SbHa, resenaloles the 



ELEMENTS OF CHEMISTRY. 131 

corresponding arsenic compound and is produced under sim- 
ilar conditions. It has not been obtained pure. The dis- 
tinction between it and arsine is given above. 

Compounds of Antimony with Oxygen.— These are — 

Sb203 Antimonous oxide, or anhydride. 

Sb205 Antimonic " " 

An intermediate oxide, Sb204, is known, but it is generally 
regarded as a compound of the other two. 

Antimonous Oxide, Sb^O^. This is found as, a mineral, 
and is also readily prepared by burning antimony in the air. 
It is like AS2O3 in many of its chemical relations, but is 
insoluble in water, less volatile, and shows some power of 
combining with acids to form salts. When boiled with a 
solution of cream of tartar (acid potassium tartrate) anti- 
monous oxide loses one atom of oxygen, and dissolves, form- 
ing tartar emetic, potassium antimony tartrate. This com- 
pound is the most famnliar preparation of antimony, as, 
unlike most of the compounds, it dissolves in water without 
decomposition. The composition is exceptional ; acid potas- 
sium tartrate is KHCiH^Oe, and the reaction with antimon- 
ous oxide is 

2KHC,H A + Sb203 = 2K(SbO)C4H,06 + H2O. 

The formula is generally as if the SbO replaced the hydro- 
gen as a monad^adicle, but if written graphically it is more 
satisfactory : 

K— (C,HA)— Sb = 0. 

C4H4O6, the radicle of tartaric acid, is a dyad. Boron and 
arsenic may take the place of antimony in this compound. 

Antimonic Oxide, Sb205, forms two acids corresponding 
to the meta- and pyrophosphoric acids. Unfortunately, the 
names of the antimony acids have been misplaced ; HSbOs 
has been called antimonic acid, and Il4Sb207 metantimonic. 
This latter name should be given to HSbOs, and H^SbgOT 



132 ELEMENTS OF CHEMISTRY. 

should be called pyrantimonic acid. Pyrantimonic acid is 
remarkable for forming the only sodium compound insoluble 
in water. The orthantimonic acid, HsSbO^, has not yet been 
obtained. 

Antimony forms compounds with chlorine, bromine and 
iodine analogous to those of phosphorus and arsenic. They 
are mostly decomposed when mixed with large quantities of 
water, yielding at first an impure, finally a pure, oxide. With 
antimonous chloride we have 

.SSbCls + 3H2O = SbClsSKOs + 6HC1. 

The oxychloride, SbClsSb^Os, becomes finally converted 
into pure antimonous oxide. 

Antimony Sulphides. Two are known : 

Sb^Ss Antimonous sulphide. 

SbsSs Antimonic sulphide. 

Antimonous Sulphide is the principal ore of antimony. 
It is found as a shining, gray, crystalline mass, fusible and 
easily oxidized by heating in the air. Hydrochloric acid dis- 
solves it easily, forming antimonous chloride and hydrogen 
sulphide. 

Sb^Ss + 6HC1 = 2SbCl3 + 3H,S. 

On the other hand, a current of hydrogen sulphide passed 
into antimony solutions produces the antimonous • sulphide as 
an orange-red precipitate, which by heating ]^comes like the 
natural form. 

Antimonic Sulphide is an orange-yellow body. 

The chemical relations of antimony are well shown in its 
sulphides. Both of them act as anhydrides, and form a 
series of salts. 

KSbSa Potassium sulphantimonite 

is strictly comparable to 

KNO2 Potassium nitrite. 



ELEMENTS OF CHEMISTRY. 133 

Antimoiiic sulphide, unlike the corresponding oxide, forms 
its salts upon the pattern of the orthophosphates. 

NagSbSi Sodium sulphantimonate 

is analogous to 

NagPOi Sodium orthophosphate. 

Sodium sulphantimonate is used in jDhotography under the 
name of Schlippe's salt. 



BISMUTH, Bi, 210. 

Sources. Bismuth is commonly found native; also as 
oxide and sulphide. It was known to the earlier chemists. 

Preparation and Properties. It is easily extracted 
from its ores by fusion in iron cylinders. It is hard, brittle, 
reddish-white and distinctly crystalline. It fuses at 507° F. 
(264° C), expanding when it solidifies. Its chemical rela- 
tions are somewhat like those of antimony, but it forms well- 
marked salts. It is not much afiected by the air. Nitric acid 
dissolves it easily. The bismuth oxides are BioO., Bi.Os, BioO^, 
Bi,05. 

Bimnuth Sesquioxide, BioOo, the only important oxide, is ob- 
tained as a yellowish powder by burning bismuth in the air or 
by heating the carbonate or nitrate. It acts as a base. 

Bismuth Nitrate, Bi(N03)3, made by dissolving bismuth 
in nitric acid, is a soluble, white, crystalline mass. When 
added to a large volume of water, a white precipitate of 
bismuth oxynitrate of irregular composition, but generally 
Bi(]S"03)3 + BioOs, is thrown down. This powder, ordinarily 
called bismuth sitbrntrate, is used in medicine and sometimes 
as a cosmetic. When it is boiled with caustic soda and a 
solution of glucose, a heavy black powder of free bismuth is 
formed. This is Boettger's test for sugar. 
12 



134 ELEMENTS OF CHEMISTRY, 

Bismidh Chloride, BiCls, is decomposed by water in a man- 
ner similar to the nitrate. 



GOLD, Au, 196.7. 

Sources. Gold occurs in the free state, often in veins in 
quartz, often in small grains in sand and gravel ; sometimes 
alloyed with silver, copper or other bodies. Gold w^as known 
to the ancients. 

Preparation. It is often extracted by washing, which 
carries off the lighter sand and dirt and leaves the gold. 
Quartz rock is first ground. It is sometimes extracted by 
amaJgamation, as described under silver. 

Properties. Pure gold is bright yellow, soft and heavy 
(specific gravity, 19.4), capable of being worked into thin 
plates or wire, and an excellent conductor of heat and elec- 
tricity. It melts at 1900° F. (1036° C.). It is unaffected by 
air, water or sulphur, or by ordinary acids even at high tem- 
peratures. Its compounds are reduced by heat alone, and by 
reducing agents in the cold. Chlorine or a mixture of nitric 
and hydrochloric acid (which contains free chlorine) dissolves 
it, forming chloride. In the pure condition it is very soft and 
can be w^elded in the cold by pressure. Gold-foil is prej^ared 
in this form for dentists' use. For jewelry, coin and other 
articles subjected to wear it is always alloyed w^ith copper 
or silver. The proportion of alloy is indicated by carats, 
pure gold being 24 carats, 18-carat gold being 18 parts gold 
and 6 parts alloy. Copper makes a red gold — silver, a green 
gold. Two sets of compounds are known, aureus and auric, 
in which the metal is respectively a monad and a triad. The 
oxides are not bases ; one appears to be an anhydride. 

AugO Aureus oxide. 
AU2O3 Auric " 



ELEMENTS OF CHEMISTRY. 135 

AiiCl Aureus chloride. 
AuCla Auric 

Auric Chloride is produced when gold is dissolved in nitro- 
muriatic acid. By adding to the liquid, free from excess of 
acid, some ferrous sulphate, the gold is thrown down as a 
brow^n powder, looking like mud. A mixture of stannous 
and stannic chlorides produces with gold chloride a purple 
precipitate called purple of Cassius, which is used for coloring 
glass and porcelain. 

Thallium, Tl, 204, was discovered by Crookes in 1861. 
It exists in some varieties of iron pyrites and in some min- 
eral waters. It acts as a monad and triad, and resembles lead 
in many points ; but its compounds are somewhat like those 
of potassium, and somewhat like those of silver. Sp. gr. 
11.8. It forms tw^o oxides, TI2O and TI2O3, the former 
being very soluble in w\ater; two chlorides, TlCl, insoluble 
in water, and TICI3, soluble in water ; and other salts of 
similar relations. Thallium compounds give a pure green 
color to flame. 

Vanadium, V 51.3, discovered by Del Eeo in 1801, is a 
rare body, found chiefly in combination wdtli iron and lead. 
It forms four oxides, VO, V2O3, VO2, V2O5, analogous to those 
of nitrogen. 

Vanadic Anhydride^ V2O5, forms salts called vanadates. 
Lead vanadate is found as a mineral. It yields compounds 
analogous to metaphosphoric acid, and also forms salts wdth 
some of the strong acids. Vanadium has acquired some im- 
portance from the possibility of making from it a good indel- 
ible ink, but the rarity of its compounds has interfered wdth 
this use. 



Carbon Group. This includes carbon, silicon, tin, 
titanium, and provisionally tungsten, zirconium, platinum, 



136 ELEMENTS OF CHEMISTRY. 

palladium and ruthenium. They are tetrads, neither strongly 
positive nor strongly negative in character. With the excep- 
tion of carbon and silicon they form feebly basic oxides. All 
of them form acid oxides (anhydrides). The group will doubt- 
less be divided when the less common members of it are more 
thoroughly studied. 



CARBON, C, 12. 

■ Sources. Carbon occurs very abundantly in nature, both in 
the free state and in combination. It is so constant a compo- 
nent of organic bodies that organic chemistry has been rather 
fancifully called the chemistry of the compounds of carbon. 
In the tissues of animals and plants it exists in union with 
hydrogen, oxygen and nitrogen. The various forms of coal 
and graphite, and certain carbonates, especially of calcium 
and magnesium, are abundant minerals. Carbon is remark- 
able for presenting itself under modifications so different that 
we should hardly suppose them to be of the same composition. 
These are — 

Amorplious Carbon, of which lampblack and charcoal are 
examples. 

Gra2jhite, or Phnnhago, which is not perfectly pure, and is 
probably a very old form of coal. 

Diamond, which is often chemically pure, but is also found 
in inferior conditions. 

Some properties are common to all these forms. They are 
all insoluble in all liquids, and infusible and unacted upon by 
acids and alkalies or by the air at ordinary temperatures. 
Heated strongly in air or oxygen, they burn, producing CO 
or CO2. 

A number of impure forms of carbon are also known. 
The special properties and origin of the forms, pure and 
impure, need only brief description. 



ELEMENTS OF CHEMISTRY. 137 

Lampblack is the deposit from smoky flames. It is a soft 
black substance, used for printing-inks and colors. It gen- 
erally contains hydrogen. 

AVoOD CHARCOAL is obtained by heating wood out of con- 
tact of air. It contains hydrogen and the mineral substances 
of the wood. 

Animal charcoal is obtained by charring blood, bones 
and other animal tissues. It is a coarse black powder. 

Wood and animal charcoals have great powers of absorp- 
tion — the former for gases, the latter for organic matters, 
especially colors and bitter principles. 

Exp. If a piece of wood charcoal be weighted so as to 
sink in some water in a tall jar, and the jar then be placed 
under the receiver of an air-pump, and the air exhausted, 
large quantities of gas, principally nitrogen, oxygen and 
carbon dioxide, will escape from the charcoal. This prop- 
erty of wood charcoal explains its use as a deodorizer. 
Gases containing hydrogen, sulphur or phosphorus are gen- 
erally entirely burned up or decomposed when absorbed in 
this way. 

Exp. If a solution of some organic color, such as litmus or cochineal, 
be filtered through animal charcoal, the color will be partly or wholly 
removed. Bitter principles, such as strychnia or the bitter of hops, 
will also be removed. Animal charcoal is extensively used for the 
decolor] zation of syrups and vegetable infusions generally. 

Graphite, called also plumbago and black lead, is desti- 
tute of any absorbent properties, and is used for lead-pencils 
and for crucibles. 

Diamond is a crystalline form of carbon, and has been 
produced artificially, though in very minute form. Its origin 
is unknown, and it is generally found in soil which has been 
transported by water. It is the hardest substance known, 
and in the impure and discolored forms it has been used with 
great advantage for the drilling and cutting of stone. 

The secondary properties, such as specific gravity, color 
and hardness, are different in the various forms of carbon. 




138 ELEMENTS OF CHEMISTRY. 

The impure forms of carbon are the varieties of coal. 

Coal has been formed from vegetable matter by a slow 
process of decay, mostly under water, by which the hydrogen 
and oxygen are in great part removed, and the carbon by 
pressure made compact. Bituminous or soft coals are thus 
produced. They always contain hydrogen and oxygen, and 
when heated evolve a variety of gases which have high illu- 
minating power, and constitute ordinary coal gas. Remains 
and impressions of plants are found in such coal. Coke is 
the residue after heating the coal. In the north-western part 
of the United States coal of comparatively recent origin 
occurs. Anthracite coal is much harder, and has very little 
hydrogen. It yields no gas on heating. It is practically a 
compact coke. The anthracite coalfields of Pennsylvania are 
the most valuable in the world, very few deposits like them 
being known. 

Gen. Cheill. Rel. Carbon is a tetrad, and combines with 
many elements. 

Tests. Carbon in the free condition is easily recognized 
by its infusibility and combustibility, and by producing car- 
bonic acid. Most of its complicated compounds yield a black 
residue of charcoal when strongly heated or mixed with strong 
sulphuric acid. 

Compounds of Carbon with Hydrogen. — Hydrogen 
and carbon combine in many proportions, forming a great 
variety of bodies. Some of the substances are produced by 
elaborate chemical operations, some by the natural processes 
of decay, many important ones by the action of heat on 
organic substances, especially coal and wood. 

Coal Gas. When bituminous coal is heated in a closed 
vessel, a large amount of gas (about five cubic feet to the 
pound in good samples) is given off*. This gas is contaminat- 
ed with tar, ammonia and sulphur compounds. The tar de- 
posits on cooling, the ammonia is removed by water, and the 
sulphur by lime ; and thus purified it constitutes illuminating 



ELEMENTS OF CHEMISTRY. 139 

gas, which is a variable mixture of hydrogen, marsh gas, 
CH4, olefiant gas, C2H4, and other gases. 

Compounds of Carbon with Oxygen. — The important 
ones are — 

Carbon monoxide CO. 

Carbon dioxide 

Carbonic anhydride 

Oxalic anhydride C2O3. 

The last is not known in the free state. 



} 



CO2. 



Carbon Monoxide, Carbonic Oxide, CO. This is pro- 
duced when carbon is burned in a deficient supply of air, as 
in stoves w^ith defective draft and in the large furnaces for 
reducing and working iron, in which an excess of fuel is pur- 
posely maintained. When steam is thrown upon burning 
coal, the reaction H2O + C = CO + H2 occurs, and the re- 
sulting mixture is available as a gaseous fuel, or may be im- 
pregnated with vapors of benzine or gasoline and used as a 
source of light. In making carbon monoxide for experimental 
process these methods are unsuitable, and application is made 
of the fact that the action of sulphuric acid upon oxalic acid 
or upon potassium ferrocyanide gives rise to the gas. 

Exp. Mix in a rather large flask some crystallized oxalic acid with 
its own bulk of sulphuric acid, and heat carefully. The mass will soon 
begin to foam and give off a mixture of CO and CO2. By passing this 
through lime-water or caustic soda^ pure carbon monoxide may be 
obtained. The reaction is 

H,C,0, + H,SO, = (H,0 + H2SO,) -f CO, + CO. 

The sulphuric acid and w^ater form a sort of combination. 

If potassium ferrocyanide be used in the proportion of about 1 part 
by weight to 13 parts of sulphuric acid and 1 of water, a large volume 
of the pure gas may be obtained. The reaction is a complicated one, 
and the mixture swells considerably, so that a large flask must be 
used. 

Properties. Carbon monoxide is a colorless, odorless, 
tasteless gas, of decidedly narcotic-poisonous properties. It 



140 ELEMENTS OF CHEMISTRY, 

is a little lighter than air. It burns easily with a clear blue 
flame. It is an unsaturated molecule, and will combine with 
chlorine and some other elements. 

Carbon Dioxide, Carbonic Anhydride, CO2, generally 
occurs in union with H.O, forming II2CO3, carbonic acid, an 
abundant substance occurring in air and water. Some of its 
salts, especially calcium and magnesium carbonates, are com- 
mon minerals. 

Carbonic Acid is produced in a great variety of ways : 

1. By the respiration of animals ; 

2. By ordinary combustion ; 

3. By fermentation and decay ; 

4. By decomposition of carbonate, either by heat or by 
acids. The last method is made available for its production 
on the small scale. 

Exp. Put some fragments of marble or chalk (CaCOg) into a retort 
or gas bottle, and add some moderately strong hydrochloric acid. The 
escape of gas occurs at once, and it may be collected by downward dis- 
placement or over water. Sulphuric acid does not answer so well, as it 
soon forms an insoluble mass in the bottle. 

The reaction is 

CaCO^ + 2HC1 = CaCl^ + H,0 + CO^. 

It is unimportant whether we regard the water and CO2 as 
separate or united. By passing the escaping gas over dry 
calcium chloride or strong sulphuric acid the pure CO2 may 
be collected. Its properties are substantially those of H2CO3. 

Properties. Carbonic acid is a colorless gas of a some- 
wdiat sharp taste. It is soluble at ordinary pressure in its 
own bulk of water, and the solubility is increased in regular 
proportion to the pressure. It is about fifty per cent, heavier 
than air, and may therefore be easily collected by running 
the delivery-tube to the bottom of the jar. 1 litre weighs 
2.07 grms. ; 47 cubic inches weigh 22 grs. It can be lique- 
fied by a pressure of 800 lbs. to the inch, and freezes at 



ELEMENTS OF CHEMISTRY. 



141 



— 70° F. ( — 56° C). It does not support animal life or or- 
dinary combustion ; but bodies of high affinity, if already in 
active combustion, will decompose it and continue to burn. 
In this way red-hot coal will produce the following reaction : 
C + CO2 = 2C0, which accounts for the production of car- 
bon monoxide in ordinary stoves. 

Exp. A Hglited taper put into the gas is instantly extinguished, hut a 
shp of ignited magnesium will continue to burn and deposit carbon. The 
reaction is Mgg -{- CO2 = 2MgO + C. 

Exp. Collect the gas in a tube over water, introduce a small piece of 
caustic soda, and quickly cork the tube. After a few moments' shaking, 
open the tube with the mouth under water, when the rise of the water 
will indicate the absorption of the gas. 

Exp. Lime-water is instantly rendered turbid by the gas, from the . 
formation of insoluble calcium carbonate, but if the quantity of tlie 
carbonic acid is in excess, the precipitate will be redissolved, producing 
what is ordinarily knowij as a hard or limestone water. This reaction is 
more fully described in connection with the calcium salts. If the clear 
solution produced in this experim.ent be boiled, the excess of CO^ will 
be expelled and the precipitate will be reproduced. 

Exp. Soap-hubbles blown with the gas sink rapidly in the air, and if 
blown with ordinary air will float in a jar of the gas. 

Exp. A large light vessel, being counterpoised on a delicate balance, 
will be thrown decidedly out of balance by substituting carbonic acid 
for the contained air. By inverting the vessel the gas will escape and 
the balance be restored. 

Exp. Carbonic acid may be easily poured from one vessel to another, 
and if a lighted taper be put at the bottom of a tall beaker, it wall be 
extinguished by the gas falling over it. 

Exp. Place a piece of potassium in a test-tube having the bottom 
Slightly broken out and arranged in 
ccmnection with a bottle evolving 
carbon dioxide, as si i own in the 
cut. Allow the gas to pass for a 
few moments, that the tube may 
become filled, and then heat the 
potassium strongly. It will take 
fire, burning with a purple light 
and depositing carbon on the side of the tube. 




142 ELEMENTS OF CHEMISTRY. 

Carbonic acid has, of course, a low diffusive power, and 
hence a tendency to accumulate at low levels if produced in 
large amounts. It is found in undue proportions at the bot- 
tom of mine-shafts and in fermenting- vats, and cases of suffo- 
cation often occur in these places. The usual method of de- 
termining whether such places are safe to enter is by lowering 
a lighted candle ; if this continues to burn vigorously, the air 
is probably safe ; if it burns feebly or is extinguished, the air 
is too rich in carbonic acid. 

Gen. Ohem. Eel. Carbonic acid may be considered a 
feeble chemical agent when compared to such bodies as nitric 
and sulphuric acids, but its continual presence in air and in 
water makes it one of the important agents in the slow changes 
which occur in nature. Assisted by the action of frost, it 
breaks down and renders soluble many kinds of rocks and 
converts them into soils. Its power of increasing the solvent 
action of water makes that liquid a very active agent in geo- 
logical changes. The chemical activity of its solution in water 
is increased by pressure, and water which is charged with it at 
great depths often emerges at the surface holding much min- 
eral matter. The release of pressure causes the gas to escape 
and gives an effervescing water. The mineral matter is at 
the same time deposited. The ordinary effervescing soda- 
water is an artificial solution of the gas under pressure. Fer- 
menting liquids owe their effervescence to the same cause, the 
retention of gas under pressure and its escape w^hen the pres- 
sure is released. Its relation to plant-life is very important. 
Under the influence of light plants decompose it, the carbon 
being absorbed and the oxygen given off. 

Carbonic acid forms a series of salts called the carbonates, 
most of which are insoluble in pure water. Monads form two 
salts. Potassium gives us, for instance, 

KHCO3 Acid potassium carbonate. 

K2CO3 Potassium carbonate. 



ELEMENTS OF CHEMISTRY, 143 

Dyads give but one salt, as 

CaCOs Calcium carbonate. 

The carbonates are decomposed by almost al] acids, and 
generally by heat. 

Tests. Carbonic acid is easily recognized by its rendering 
turbid a solution of calcium hydrate (lime-water) or barium 
hydrate (baryta-water). It turns litmus to a wine-red, the 
blue color being restored on boiling ; solution of cochineal is 
not affected. 

Combustion and the Structure of Flame. — The ele- 
ments carbon, hydrogen, oxygen and nitrogen, and their 
compounds, form by far the greater part of all the material 
objects around us, and are the especial elements of the tis- 
sues of animals and plants from which our fuel and illumi- 
nating agents are directly or indirectly derived. The process 
of burning is much the same as the process of decay. It is 
the absorption of oxygen and the formation of carbonic acid, 
water and free nitrogen, or sometimes of ammonia and nitric 
acid. The phenomenon of flame attracted the attention of 
the most ancient investigators, and it was by them considered 
a form of matter. We know now that ordinary flame is a 
process ; it is gas of some kind in the act of uniting with the 
oxygen of the air, the operation being attended with the pro- 
duction of light, heat and other forms of force. 

Formerly the terms " combustible'' and '^supporter of com- 
bustion " were much used ; carbon, phosphorus and hydrogen 
being called combustible elements, oxygen and chlorine sup- 
porters of combustion. This distinction is now abandoned ; 
the action is a mutual one, and the supporter of combustion 
may easily be made the combustible. True flames may be 
produced in which none of the ordinary agents are used. 

The flame of a candle or other body burning free in i\\Q 
air is generally pointed or conical, due to drafts of air which 
strike the side of the flame and rise, drawing in toward the 



144 



ELEMENTS OF CHEMISTRY. 




centre. AYhen, as in our gas-burners, the burning 
body is supplied under pressure, the form of the 
flame is different, but the different parts are still 
conveniently called cones. 

If we examine common gas or candle flame, we 
find that it consists of three parts : 

(a) An inner space of a bkie color; 

(h) A shell of brightly luminous particles ; 

(c) A fringe of feebly luminous particles. 

The inner cone is the point at which the gas that is burn- 
ing is produced or escapes. In the flame of a candle or of 
coal oil the gas is the result of a destructive distillation of the 
fat or oil. This gas contains carbon and hydrogen. At its 
outer edge it meets the air ; most of the hydrogen is con- 
verted into water, the carbon is set free in solid but finely 
divided condition in union with some hydrogen, and this solid 
is intensely heated by the combustion of the hydrogen. This 
is the source of the light, and forms the second cone. The 
finely-divided matter passes outward and gradually burns, 
producing the feeble fringe of light, which is the third cone. 
It is obvious that with bodies which are deficient in carbon, 
or which are burned in a supply of oxygen suflicient to con- 
sume the carbon before it can be set free, very little light 
will be produced ; on the other hand, if the quantity of car- 
bon is large, the flame will not be able to heat it above a red 
heat, and the supply of oxygen may not be sufficient to burn 
it up ; and we then have a lurid, smoky flame. 

The following experiments show the general nature of flame 
and the manner of studying it : 

L The flame of pure hydrogen gives out very little light. If solid 
particles of charcoal dust, platinum wire, etc. be introduced, they will 
become luminous. 

2. If a small glass tube be introduced into the centre cone, a quantity 
of the unburnt gas will pass out, and may be burned at the other end 
of the tube. The temperature of this interior cone is very low. 



ELEMENTS OF CHEMISTRY. 



145 




3. Alcohol, which contains very little carbon, burns without much 
light ; turpentine, which contains much carbon, burns with a red flame 
and smoke. By making a mixture of the two a pretty good flame may 
be obtained. 

4. A piece of paper or card, being held for a moment low 
down in a spirit-lamp flame, will be charred in a ring, show- 
ing that the interior of the flame is not burning. 

5. Anything which cools the carbon down below its burn- 
ing-point will cause it to deposit in the solid form ; hence 
the formation of soot or lampblack when flames come in 
contact with cold surfaces. 

6. If a chimney is placed over a smoky 
flame, the increased draft causes a more 
abundant supply of air, and the carbon is 
completely burned. This is the reason for 
the use of chimneys in coal-oil lamps. 

The accompanying illustrations show 
methods of arranging lamp-chimneys for 
showing the movements of heated air. 
The direction of the current may be shown 
by igniting a piece of brown paper which 
has been soaked in a strong solution of 
nitre and dried. 

When the flame is disposed in the form 
of a ring, air being admitted without and 
within the ring, the arrangement is called 
an argand burner. The German student's 
lamp is an excellent form of argand. 

7. If a flame be suddenly cooled, as by 
the introduction of a coil of wire or a sheet 
of wire gauze, the combustion will cease 
and the mixture of gas and air will escape. 
This can be easily shown by putting a piece 
of wire gauze across a gas flame, when it 
will be found that the flame will stop at the gauze, but a combustible 
mixture of gas and air will pass through it. Similarly, the gas may 
be lighted above the gauze and the flame will not run back. If the 
gauze becomes hot, the flame will pass through. This principle is made 
use of in the Davy's safety-lamp for preventing explosions in mines. 
It consists of a lamp arranged so that no air or gas can get in except 
through fine gauze. If an explosive mixture finds its way to the 

13 




146 ELEMENTS OF CHEMISTRY. 

flame, its combustion is limited to the interior of the lamp, at least 
for a time. 

8. If common coal gas be mixed with air, it will burn with a non- 
luminous, smokeless fiame ; and such lamps are now used very largely. 
In the simplest form, the Bunsen burner, the air is drawn in through 
openings at the bottom. A great variety of these lamps is now made, 
and Mr. Fletcher of England has brought the use of gaseous fuel to 
high perfection, so that it bids fair to come into almost exclusive use. 

When a current of air is driven into a flame its tempera- 
ture is increased. This is the cause of the efficacy of the 
mouth blowpipe and of blast-lamps. 

When mixtures of gas and air are ignited, combustion may 
occur through the entire mass at once. This constitutes an 
explosion. Recent research has shown that violent explosions 
may occur from the rapid ignition of fine particles of coal or 
flour diffused through the air. 

Flame Tests.— Many elements give characteristic colors 
to flames. Such tests are very delicate, and when applied to 
pure substances very satisfactory. When several colors are 
present, one color may conceal the other, and thus the test be 
incomplete. By passing the light through a prism the colors 
are separated, and each may be recognized.. The apparatus 
for this purpose is called a spectroscope. Observations with 
it show that most elements give out light which is made up 
of several colors. 



Carbon Bisulphide, CS2. This body is precisely analo- 
gous to carbon dioxide. It is produced by passing vapor of 
sulphur over red-hot charcoal. It is a colorless liquid, which, 
when quite pure and in large quantity, has a rather pleasant 
odor, but when impure, and especially when diffused through 
the air in small quantity, is quite disagreeable. It has high 
dispersive power — that is, separates widely the various colors 
of the spectrum — and is often used in optical apparatus. It 
is very volatile and inflammable, and has high solvent pow- 



ELEMENTS OF CHEMISTRY. 147 

ers, dissolving sulphur, phosphorus and most oils and fats, 
and is much used for such purposes. Its vapor will take fire 
much below a red heat. 

Exp. Put a few drops of CS2 at the bottom of a small glass vessel 
and allow them to evaporate. If a glass heated to about 300° F. be 
introduced, the vapor inflames. The products of combustion are CO2 
and SO2. The analogy between CO2 and CSg has been pointed out 
elsewhere. 

Carbon Chlorides. Carbon forms with chloride at least 
four compounds: 

C2CI2 Carbon monochloride. 

C2CI, " dichloride. 

C2CI6 '' trichloride. 

CCI4 " tetrachloride. 

These cannot be prepared by the direct union of their ele- 
ments, but are mostly the result of the successive substitu- 
tion of chlorine for hydrogen. Marsh gas, CH^, for instance, 
yields, by such action, the following compounds : 

CH3CI Monochlorinated marsh gas. 

CH2CI2 Dichlorinated 

CHCI3 Trichlorinated 

CCl, Tetrachlorinated " 

The third body, CHCI3, is chloroform ; the fourth is carbon 
tetrachloride, the most important of the carbon chlorides. 
It is a colorless, volatile liquid, which acts as a powerful 
anesthetic. 

Cyanogen, CN. Cyanogen is electro-negative, and in its 
chemical relations resembles such elements as CI, Br and I. 
It forms compounds called cyanides. In all of these it acts 
as a monad ; thus we have hydrogen cyanide, HCN, potas- 
sium cyanide, KCX. Dyads require, of course, two mole- 
cules of cyanogen. Calcium cyanide is CaC2N2 or Ca (CN)2. 
The svmbol Cy is often used in formulae instead of the sym- 
bol Ck. We write HCy instead of HCIST, KCy instead of 
KCN, CaCy2 instead of the formula for calcium cyanide just 



148 ELEMENTS OF CHEMISTRY. 

given. The chemistry of cyanogen is more conveniently con- 
sidered in connection with organic compounds. 



SILICON, Si, 28. 



Sources. Silicon never occurs in the free state, but is 
found very abundantly as oxide, SiOa, and as silicates. It 
was discovered by Davy in 1807. 

Preparation. By methods similar to those used for 
boron. 

Properties. Silicon exists in three forms, amorphous, 
graphoidal and diamond, corresponding to those of carbon. 
When strongly heated in the air it burns, producing SiOa. 

Gen. Ohem. Rel. Silicon is a tetrad, and is related to 
carbon in many ways, especially in the capacity for assum- 
ing allotropic forms. Compounds have been obtained in 
which it has replaced carbon. Silicon also has chemical 
relations to tin and titanium. 

Silica, Silicic Anhydride, SiOs. This is a widely dis- 
tributed body, occurring free as common sand, chalcedony, 
quartz, etc., and in combination forming silicates in great 
variety, of which clay, granite, feldspar and sandstones are 
instances. A very large proportion of the solid substances in 
the earth's crust are forms or compounds of silica. Silica 
exists in the stems of grasses and in the teeth and bones of 
animals. 

In its pure forms silicic anhydride is a colorless, nearly 
infusible and insoluble solid, destitute of chemical ac- 
tivity. In nature it often occurs in large six-sided crys- 
tals of the form shoAvn in the cut. These are sometimes 
ruby-colored, and are then called amethyst. XJn crys- 
tallized silica also occurs in variously colored condi- 



ELEMENTS OF CHEMISTRY, 149 

tions — agate, jasper, chalcedony, onyx, etc. In all its forms it 
is converted into a silicate by fusion with sodium carbonate, 
and when lime, lead oxide or other metallic oxides are mixed 
^vith the sodium silicates, we get the various forms of glass. 

Silicic Acid, Orthosilicic Acid, H^SiOi. This cannot be 
produced by direct union of water with the natural forms of 
silica, but is obtained when silicates are decomposed by acids. 
If the sodium silicate be treated with hvdrochloric acid, the 
following reaction occurs: 

Na.SiO, + 4HC1 = 4NaCl + H.SiO,. 

The silicic acid and salt remain in solution in the water in 
which the HCl was dissolved. By placing the solution in a 
vessel made of parchment-paper and floating it in water, the 
salt passes out of the vessel and leaves a pure solution of 
silicic acid. This process is called dialysis. Solution of 
silicic acid is tasteless and feebly acid to litmus. By evap- 
oration it forms a gelatinous mass which can be brought to 
the composition H^SiOs (metasilicic acid), and by further 
heating gives the insoluble anhydride. The chemistry of 
silicic acid is complicated. It presents some of the charac- 
ters of phosphoric acid in its power of forming different acids 
by taking up different proportions of water. Many of the 
natural silicates . are decomposed and rendered soluble by the 
combined action of frost and carbonic acid. In this way 
soils are formed and extensive geological changes ultimately 
produced. 

Silicon combines with the halogens, forming bodies resem- 
bling the corresponding carbon compounds. 

Silicon and fluorine have a strong affinity, and silicon 
fluoride, SiF^, is easily prepared by the action of hydrofluoric 
acid upon silicic acid or any silicate. It is a colorless gas, 
which is decomposed by water, yielding gelatinous silicic acid 
and a double fluoride of silicon and hydrogen. 

3SiF, + 4H,0 = H.SiO, + 2( 2HF,SiF,). 

13* 



150 ELEMENTS OF CHEMISTRY, 

The latter body is often called hydrofluosilicic. acid. Silicon 
combines with positive elements, forming silicides, but many 
of these are of uncertain composition. Hydrogen silicide, 
H^Si, the most interesting, is prepared by dissolving mag- 
nesium silicide in hydrochloric acid. It resembles hydro- 
gen phosphide in taking fire spontaneously when impure. 
In its composition it is analogous to marsh gas, CH^. 



TIN, Sn, 118. 



Sources. Tin occurs principally as dioxide, called tin- 
stone. It was know^n to the ancients. 

Preparation and Properties, The ore is roasted and 
reduced with charcoal. Tin is white, soft and easily beaten 
into foil, but is not tough ; specific gravity, 7.28. It fuses at 
442° F. (228° C), and resists very well the action of the air 
and of cold acids. Nitric acid forms an insoluble dioxide. 
Tin forms several valuable alloys — pewter, gun-metal, type- 
metal, bronze and solder, elsewhere described. Speculum- 
metal, used for metal mirrors, is an alloy of copper and tin ; 
glass mirrors are coated with an amalgam of tin. Tin plate 
is iron coated with tin by dipping it into a bath of the melted 
metal. 

Two series of tin salts are known — stannous, dyad, and 
stannic, tetrad. 

Stannous Oxide, SnO, is a feeble base, but is not import- 
ant. 

Stannous Chloride, SnCl2, is formed by dissolving tin in 
hydrochloric acid. The solution deposits white crystals con- 
taining 2H2O. They dissolve in water, but are generally 
quickly decomposed into an oxychloride, which precipitates. 
Stannous chloride is an unsaturated molecule, and tends to 
take up chlorine or oxygen, for which reason it is used as a 



ELEMENTS OF CHEMISTRY. 151 

reducing agent. When mixed ^vith mercuric chloride, mer- 
cury is set free and stannic chloride formed. 

• HgCJ^ + SnCl, = Hg + SnCl,. 

Stannous chloride is used by the dyer as a mordant under 
the name of tin crystals. 

Stannous Sulphide, SnS, is found as a mineral, and is 
obtained artificially by the action of hydrogen sulphide lipon 
stannous chloride. 

SnCl2 + H^S = SnS + 2HC1, 

Stannic Oxide, SnO,,, Stannic Anhydride, is found as a 
mineral ; also produced by burning tin in the air, by oxidiz- 
ing it with nitric acid and by adding an alkali to stannic 
chloride. Like silicic anhydride, it forms different acids 
according to the method of production. When tin is heated 
with nitric acid, a white powder is obtained, which forms com- 
plicated salts called metastannates. When an alkali is added 
to the chloride an acid is formed, having the composition 
HaSnOs, forming salts called stannates. This latter acid is 
analogous to metasilicic, HaSiOa, and should have been called 
metastannic. 

Stannic Chloride^ Tin Tetrachloride, SnCl^, Libavius' Fum- 
ing Liquor. This body is largely used by dyers under the 
name of nitro-muriate of tin, being made by the action of a 
mixture of nitric and muriatic acid on tin. It is a colorless 
fuming liquid, boiling at 239.5° F. (115.3° C). 

Stannic Sulphide, SnS2, Mosaic Gold, is made by passing 
hydrogen sulphide into stannic chloride. It is a bronze- 
colored powder used in printing and coloring. 

Titanium, Ti, 50, discovered by Gregor in 1709, exists as 
titanic anhydride, TiOo, and also in some iron ores. 

Tantalum, Ta, 182, discovered by Hatchett in 1801, and 
Niobium, Ni, 94, are found in some rare minerals. 

Tungsten, W, 184, discovered by Bergman in 1783, exists 



152 ELEMENTS OF CHEMISTRY. 

as a manganese-iron tungstate, called wolfram, and as calcium 
tungstate (scheelite.) The only important compound of the 
metal is tungstic acid, H2WO3. Sodium tungstate has been 
employed for rendering dress goods fireproof. 

Zircoiiium, Zr, 89.5, discovered by Klaproth in 1789, may 
belong in the aluminum group. It exists as oxide in the 
rare mineral zircon. 



PLATINUM, PL 197.1. 

Sources. Platinum occurs native, also alloyed with the 
elements of its class, and with gold and silver. It was dis- 
covered by Wood in 1741. 

Preparation and Properties. The ore is purified by 

solution in aqua regia and precipitation of the platinum as 
ammonio-platinum chloride, 2AmCl + PtCl^. This is de- 
composed by heat, the platinum being left in a spongy 
state. This is compressed into a small bulk and hammered 
while red hot. It can also be fused in the flame produced by 
burning a mixture of oxygen and hydrogen. 

Platinum is hard, white and very heavy ; specific gravity, 
21.5 ; it fuses only at a very high temperature. It resists 
perfectly the action of the air and of most chemical agents, 
and for this reason is largely used in chemical operations. It 
dissolves in hot aqua regia, forming platinum tetrachloride, 
PtCl^. Many elements, especially zinc, tin, lead and silver, 
when melted with platinum dissolve it easily, forming fusible 
alloys. Platinum forms two series of compounds ; its oxides 
are only feebly basic. 

Platinum Tetrachloride, or Platinic Chloride, PtCl^, is a red 
or brown deliquescent mass obtained by dissolving platinum 
in aqua regia, and evaporating the solution to dryness. It 
forms yellow granular precipitates with potassium and ammo- 



ELEMENTS OF CHEMISTRY, 153 

niiim salts, but not ^vith those of sodium, and is of great use 
in analysis for the separation of potash and soda. 

Palladium, Pd, 106.5, discovered by.WoUaston in 1803, 
exists associated with platinum and gold. It is hard and 
Avhite, specific gravity, 11.6, and is not easily oxidized. Ham- 
mered palladium absorbs 640 times its volume of hydrogen, 
forming an alloy. Two series of palladium compounds are 
known, in which it is respectively dyad and tetrad. 

EuTHENiUM, Eu, 104.4, discovered by Claus in 1846, is 
found with platinum, also as a sulphide. It is hard and 
brittle, difficult to fuse and to oxidize; specific gravity, 11.4. 
It acts as a dyad and tetrad. 



Calcium Group includes calcium, barium, strontium and 
lead. They are electro-positive dyads, not found in the free 
state in nature, and form oxides slightly soluble in water and 
much less caustic than the alkalies, but often called alkaline 
earths. Their sulphates, carbonates and phosj)hates are in- 
soluble. They each form a dioxide which is apparently neither 
basic nor acid. 

CALCIUM, Ca, 40. 

Sources. Calcium occurs abundantly as sulphate, car- 
bonate, phosphate and fluoride. It was discovered by Davy 
in 1808. 

Preparation and Properties. Calcium is prepared by 
decomposing the chloride either by electricity or by sodium. 
It is light yellow, hard and malleable ; oxidizes easily. 

Calcium Oxide, Quicklime, CaO, is obtained by heating 
the carbonate to redness. 

CaCOa^CaO + CO,. 

Quicklime ('' quick " means alive or active) is a white. 



154 ELEMENTS OF CHEMISTRY, 

infusible solid, which neutralizes the most powerful acids and 
combines with water with great energy, forming 

Calcium Hydrate, Slaked Lime, CaB[202, a soft white 
caustic powder, slightly soluble in cold water (about 9 grains 
to* the pint), less so in hot. The solution, known as lime- 
water, is used as a test for free carbonic acid, which produces 
a precipitate in it. 

Slaked lime mixed with sand constitutes mortar. The 
cause of the hardening of mortar is not definitely known; 
calcium carbonate and silicate are formed, but only in small 
amounts. 

Lime is used in agriculture to assist in decomposing the 
silicates in the soils. 

Calcium Carbonate, CaCO^, occurs abundantly and in a 
variety of forms. It is the chief constituent of shells and of 
coral. In a non-crystalline condition it is seen as chalk, mar- 
hie and limestone; in crystals it forms Iceland spar and ar- 
ragonite. It can be prepared artificially by adding sodium 
carbonate to calcium chloride. 

CaCl^ + Na^COa = CaCOa + 2NaCl. 

Calcium carbonate is a white solid, insoluble in water and 
decomposed by a red heat. It dissolves in water containing 
carbon dioxide, for which reason most spring- and river-waters 
contain it. When present in an amount more than a grain 
or two to the gallon, a hard water is formed, which has the 
property of curdling soap and preventing the formation of a 
lather. This is due to precipitation of insoluble calcium salts, 
formed from the fat-acids of the soap. Boiling the water will 
expel the carbon dioxide and precipitate the calcium carbon- 
ate, thus softening the w^ater. The same result is attained by 
adding clear lime-water, which combines with the carbon di- 
oxide. Water which can be softened by these methods is said 
to be temporarily hard. It is probable that the calcium car- 
bonate exists in the water as an anhydro-carbonate, anal- 



ELEMENTS OF CHEMISTRY. 155 

ogous to borax. The excess of carbon dioxide may also be 
expelled by exposure of the water to air, and the calcium 
carbonate will then be deposited. Such an action occurs, for 
instance, in caves, forming stalactites and stalagmites. 

Calcium Sulphate, CaS04, usually occurs as a mineral, . 
crystallized with 2H2O, constituting selenite, gypsum and ala- 
baster, sometimes, however, anhydrous. It is soluble in about 
400 times its weight of cold water. It is a frequent ingre- 
dient of spring- and river-water, causing the same effect of 
hardness mentioned above; but as the sulphate does not owe 
its solubility to carbon dioxide, boiling, except for a long time, 
does not soften the water, and hence the condition is called 
permanent hardness. When the crystallized mineral is heated 
moderately, it loses its water of crystallization and becomes a 
soft white powder (plaster of Paris), which when mixed again 
with water reabsorbs it and becomes a hard mass, expand- 
ing slightly in bulk, and thus suited for taking casts of any 
object. 

Calcium Phosphate, Ca3(P04)2, occurs in bone and in mod- 
ified form in some mineral deposits. Its chief use is in fertil- 
izers and in the manufacture of phosphorus and its com- 
pounds. ■ It- is insoluble in water. 

Calcium IIj/2?ophosphite, Ca(PH202)2, is prepared by boiling 
phosphorus with lime, as indicated on page 122. It is used in 
medicine. By substituting barium hydrate for the lime, bar- 
ium hypophosphite is formed, from which hypophosphorous acid 
can be obtained as a syrupy liquid, easily decomposed and 
having powerful reducing action. 

Calcium Chloride, CaCla, is easily obtained by dissolving 
the carbonate in hydrochloric acid. 

CaCOs + 2HC1 = CaCl2 + H2O + CO2. 

It is very soluble in water, and the solution on evaporation 
forms crystals of the composition CaCls + GHoO, which melt 
and become anhydrous at about 450° F. (232° C). The 



156 ELEMENTS OF CHEMISTRY. 

anhydrous salt has a powerful affinity for ^vater, and is used 
for drying gases. It also absorbs ammonia gas and combines 
with alcohol. 

Calcium Hypochlorite, BleacMng-Powder. This body is 
produced by passing chlorine into slaked lime, keeping the 
mixture cool. The reaction should be, in theory, 

2CaHA + CU = Ca(ClO)2 + CaCl^ + SH^O. 

The exact composition of the commercial bleaching-pow- 
der is, however, still undetermined ; it appears to contain 
some unchanged calcium hydrate, but is probably mainly a 
combination of calcium hypochlorite, Ca(C10)2, with calcium 
chloride, CaCl2. Bleaching-powder, when in good condition, 
is a loose, dry, white powder, with a faint and not disagree- 
able odor. If it smells of chlorine it is in bad condition. 
It dissolves in w^ater. The solution possesses strong bleach- 
ing and deoxidizing powers, for which purposes it is largely 
used. Acids, even carbonic acid, decompose it, setting chlorine 
free. 

Ca(C10)„ CaCl^ + 2H2CO3 = 2CaC03 + 211,0 + CI,. 

The commercial salt is often erroneously called chloride of 
lime, 

Oalcium Fluoride, CaF„ Fluor Spar, is the principal 
source of the fluorine compounds. It is found as a mineral, 
often in very fine colored crystals, wdiich become luminous 
when heated. 

Tests. Calcium compounds give to flame a reddish color, 
which is a mixture of orange, green and faint blue. Sul- 
phuric acid does not precipitate dilute solutions of calcium 
salts, as calcium sulphate is somewhat soluble in water. The 
usual test for calcium is ammonium oxalate, which throws 
down a white precipitate of calcium oxalate. 



ELEMENTS OF CHEMISTRY, 157 

BARIUM, Ba, 137. 

Sources, etc. Barium occurs principally as sulphate and 
carbonate. It was discovered by Davy in 1808. It is pre- 
pared from the chloride by electrical decomposition, and is a 
pale yellow, easily-oxidized solid, of a specific gravity of 4. 

Barium Oxide, Baryta, BaO, is obtained by heating the 
nitrate. It easily takes water, forming barium hydrate, 
Ball202, which is soluble in about 20 parts of water, the 
solution being rendered turbid by very small amounts of 
carbonic acid, and hence used as a test. 

Barium Dioxide, BaOa, is formed by heating BaO in a cur- 
rent of air. It is used in making hydrogen dioxide. 

Barium Carbonate, BaCOg, is found in nature as wither- 
ite, and is also made artificially. It is insoluble in pure 
water, and used in some analytical operations. 

Barium Sulphate, BaSO^, Barytes, Heavy Spar, is found 
abundantly as a mineral, often forming the gangue or rock 
surrounding metallic veins. It is a very heavy, w^hite, insol- 
uble solid, often finely crystallized. It is used as a substi- 
tute and adulterant for white lead, and also to adulterate 
various other articles. When barium salts are mixed with a 
sulphate the barium sulphate is thrown down. Heated with 
carbon, it becomes a soluble sulphide, and can in this way be 
used as a source of the other barium salts. 

Barium Nitrate, Ba(N03)2, is used as a test solution for 
sulphates and in making green fire. 

Barium Chloride, BaCl2, is also used as a test. 

Tests. Barium communicates to flame a yellowish-green 
color, which the spectroscope shows to contain several distinct 
shades. 

Sulphuric acid produces in barium solutions a white pre- 
cipitate of barium sulphate, insoluble in water and acids. 

Strontium, Sr, 87.5, resembles barium closely in its com- 
11 



158 ELEMENTS OF CHEMISTRY, 

pounds and chemical relations. It occurs as sulphate, celes- 
tine, and carbonate, strontianite. It may be prepared simi- 
larly to barium. It was discovered by Davy in 1808. 
Strontium nitrate is used in making red fire. 

Tests. Strontium compounds give to flame a crimson tint, 
which is a mixture of red, orange and blue. Its solutions 
produce Avith sulphuric acid a white precipitate resembling 
that given by barium. The color imparted to flame is suf- 
ficient distinction. 



LEAD, Pb, 207. 



Sources. Lead occurs abundantly as sulphide {galena), 
and in small quantity as carbonate, sulphate and phosphate. 
It was known to the ancients. 

Preparation. The sulphide is the common ore. It is 
roasted in a free supply of air, by which a portion is con- 
verted into sulphate. The mixture is then highly heated, 
and the following reaction occurs : 

PbSO, + PbS = Pb^ + 2SO2. 

Properties. Lead is soft, bluish- white, and not capable 
of being made into very thin sheets or wire. It resists the 
action of air and of some strong acids, for which reason it 
is used in chemical apparatus, as in the manufacture of sul- 
phuric acid. Pure water, free from air, has no action on 
lead, but aerated water soon oxidizes and dissolves it in small 
quantity. The presence of sulphates and phosphates inter- 
feres with this action, because they precipitate insoluble lead 
compounds. The composition of a water is thus a matter of 
some importance when the supply comes through lead pipes, 
and the presence of a few grains of calcium or sodium sul- 
phate to the gallon is a good preventive of lead-poisoning. 
Lead melts at 617'' F. (325° C), and boils at a white heat. 
Specific gravity, 11.5. 



ELEMENTS OF CHEMISTRY. 159 

It forms some important alloys. Type-metal contains 4 
parts lead and 1 part antimony ; solder, about equal parts of 
lead and tin ; pewter, 1 part lead and 4 parts tin. 

Lead Monoxide, Litharge, Massicot, PbO, is usually made 
by heating lead in the air. It is a yellowish or reddish pow- 
der, slightly soluble in water and neutralizing the most pow- 
erful acids. It fuses at a red heat, and in this condition com- 
bines easily with silica, for which reason it is often used in 
glazing earthenware, but such glaze is easily attacked by 
acids and may give rise to lead-poisoning. Lead oxide is 
used in paints and cements. 

Lead Dioxide, Puce or Brown Oxide, PbOz, may be obtained 
by the action of nitric acid upon red lead. It is a brown 
powder insoluble in water, and having some of the charac- 
ters of an anhydride. It is an oxidizing agent. 

Red Lead, Minium, usually PbgO^, is a mixture of PbO 
and PbOa. It is obtained by heating litharge in the air for 
some hours. It forms a bright red powder, not constant in 
composition. It is used as a coloring material and in the 
manufacture of glass. 

Lead Sidphide, PbS, is abundant as a mineral, forming 
large cubical lead-colored crystals. Lead sulphide is easily 
made artificially by passing hydrogen sulphide into lead 
solutions; thus: 

Pb(]Sr03)2 + H^S = PbS + 2HNO3. 

Lead Carbonate, VhCOs, White Lead, occurs as a mineral, 
but is now made artificially on a very large scale for use in 
paints. The most used method is know^n as the Dutch pro- 
cess. Thin sheets of lead are loosely rolled up and set in 
earthen jars, at the bottom of which some vinegar is placed. 
The jars are then piled in rows and covered wdth spent tan, 
but the air is not entirely excluded. The tan decomposes, 
producing heat and evolving carbon dioxide. A lead oxy- 
acetate is first formed and then converted into carbonate. 



160 ELEMENTS OF CHEMISTRY, 

The process requires some weeks, and the product is then 
ground, and for use is mixed with fixed oils. Lead carbon- 
ate is a white, opaque powder, insoluble in pure water. The 
white lead of commerce is an oxy-salt of varying composi- 
tion, approximately 2PbC03 + PbO + H2O. 

Lead Sulphate, PbS04, is thrown down when lead salts are 
mixed with any sulphate. It is a white insoluble powder. 

Lead Chloride, PbCla, is not very soluble in cold water, so 
that when a chloride is added to a lead salt a precipitate 
often occurs. It forms slender crystals, which are tolerably 
soluble in boiling water. 

Lead Lodide, Pbiz, is easily produced by adding potassium 
iodide to lead solution. It forms a bright yellow powder 
sparingly soluble in cold w^ater. If dissolved in boiling 
water, the solution on cooling will deposit the iodide in 
crystals. 

Tests. Lead compounds give a pale green color to gas 
flame ; with the electric spark a mixture of violet, green and 
yellow is produced. Sulphuric acid precipitates white lead 
sulphate; potassium chromate gives a yellow chromate 
(chrome yellow) ; potassium iodide, yellow lead iodide, solu- 
ble in boiling water ; and hydrogen sulphide, a black lea.d 
sulphide. 



Copper Group. This includes copper and mercury. 
They are electro-positive dyads, but also form a series of 
compounds in which they are apparently monad. In this 
latter condition they form chlorides insoluble in water, thus 
being connected with silver and thallium. 

COPPER, Cu, 63. 

Sources. Copper occurs native — i. e. in the free state — 
in large masses, also abundantly as sulphide, copper pyrites, 
and as oxide, silicate and carbonate. It was known to the 



ELEMENTS OF CHEMISTRY. 161 

ancients. In small amounts it is widely, distributed in nature, 
occurring in many articles of food, and generally in the human 
body, especially in the brain. 

Preparation. The native copper of course requires very 
little preparation. The sulphide and carbonate are decom- 
posed by roasting and successive meltings. 

Properties. Copper is distinguished by its red color. It 
is heavy, specific gravity, 8.9 ; hard, and can be worked into 
thin plates or wire ; melts at 1996^ F. (1091° C). It con- 
ducts heat and electricity very well, and resists the action of 
the air, but is slightly oxidized and dissolved by acids when 
in contact with air. Even sea-water and the acids of fruits 
will produce this effect, and hence the danger of using copper 
vessels for kitchen purjDoses. It furnishes some valuable alloys 
— brass, gun-metal, etc. An alloy of copper with hydrogen, 
CU2II2, has attracted some attention on account of its supposed 
theoretical relations. Copper compounds form two sets of 
salts; in the most important, the cupric series, the metal is 
dyad; in the other, cuprous, two atoms of copper are sup- 
posed to act together as a double atom. The condition is 
usually explained by graphic formulae (see page 31), thus : 

Copper in cupric salts. Copper in cuprous salts, 

— Cu— — Cu— Cu— 

The cuprous salts are mostly colorless ; the cupric salts are 
green or blue. 

Copper Monoxide, Black Oxide, CuO, is prepared by heating 
copper in air or by roasting the nitrate. It is a heavy black 
powder, dissolving in acids. Heated in a current of hydrogen 
it is easily reduced. Copper oxide is used in organic analysis. 
Copper hydrate, CuH^Os, formed when copper salts are mixed 
with an alkali, is a bluish-green mass, dissolving in ammonia, 
producing a clear, deep-blue liquid of complicated composi- 
tion. With potassa and soda no solution occurs except in the 
presence of certain organic bodies, especially sugar, when a 

14* 



162 ELEMENTS OF CHEMISTRY. 

clear blue solution is also formed. If such solution is boiled, 
the cupric hydrate is changed to cuprous, which is precipitated 
as a red or orange powder. This reaction is a useful test for 
sugar (g. 1'.). 

Cojpper Sulphide, CuS, Copper Pyrites, occurs as a mineral, 
and is easily produced as a black precipitate by mixing copper 
solution with hydrogen sulphide. 

CuSO, + H^S = CuS + H^SO^. 

Cojjper Carbonate, CuCOg, appears not to be known in the 
pure state. Various oxycarbonates, malachite and azurite, 
exist as fine minerals, and similar compounds are obtained by 
the addition of carbonates to copper salts. The natural forms 
are used for ornamental articles, the artificial form for paints. 

Copper Sulpha^te, CuSOi, Blue Vitriol, Blue Stone, is 
formed by dissolving copper or its oxide in sulphuric acid. 
It forms large blue crystals soluble in water, and having the 
composition CuSO^ + 5II2O. When heated, the water of 
crystallization is driven out and the salt becomes a soft 
white powder. 

Copper Nitrate, Cu(K"03)2, is a residue from the preparation 
of nitric oxide. It has little importance. 

Copper Chloride, CUCI2, is in green crystals, soluble in 
w-ater. It forms a number of double salts. An oxychloride 
is used as a paint. 

Cop)per Arsenite, Scheele's or Paris Green, CuIIAsOs, is a 
bright green powder, obtained by mixing an alkaline arsenite 
with cupric sulphate. It is used for killing potato-bugs and 
also as a color. It is a violent poison. A compound of 
acetate and arsenite is known as Schweinfurth green. 

Cujjrous Salts. These are of little importance. Cuprous 
Oxide, CU2O, has already been mentioned as the result of the 
action of sugar on a mixture of caustic alkali and cupric 
hydrate; Cup)rou& Chloride, CuoCla, is a white solid, insol- 



ELEMENTS OF CHEMISTRY. 163 

uble in water. The cuprous salts are easily converted into 
cupric. 

Tests. Copper gives a green tint to flame ; with the electric 
spark it gives a mixture of violet and green light. Ammonia 
gives a bluish-green precipitate ; and on adding it in excess a 
deep blue color. Potassium ferrocyanide gives a mahogany 
brown precipitate of copper ferrocyanide. Hydrogen sulphide 
gives a brown precipitate of copper sulphide. A clean piece 
of iron immersed in a solution of copper becomes quickly 
covered with a bright red coating of copper. 



MERCURY, Hg, 200. 

Sources. Mercury is found native, and as the sulphide 
(cinnabar) in Spain, California, Japan and China. It was 
known to the ancients. 

Preparation. The cinnabar is roasted; the sulphur is 
evolved as sulphur dioxide (SO2), the mercury volatilizes, 
and the vapor is condensed in earthen pipes. 

Properties. Liquid at the ordinary temperature, freezing 
at —40^ F. and C, and boiling at 675° F. (357° C.) ; when 
pure it does not tarnish in dry or moist air, but above 300° C. 
it absorbs oxygen and passes into the red oxide. It is largely 
employed in the processes for extracting silver and gold from 
their ores, and is used in medicine. It is very lustrous and 
heavy ; specific gravity, 13.56. Mercury has the power to 
dissolve other elements, forming alloys which are known as 
amalgams. These are either soft or hard according to the 
quantity of mercury used. Mirrors are coated with an amal- 
gam of tin. Dentists use extensively various amalgams for 
filling teeth. When mercury is triturated with a soft sub- 
stance, it can be so finely divided as to lose all its lustre and 
appear as a bluish or gray powder, which is used in medicine 
under the name " blue pill." The vapor is 100 times as heavy 



164 ELEMENTS OF CHEMISTRY. 

as hydrogen — half as heavy as theory would require. Two 
series of salts are known, corresponding to the copper salts, 
and called resj)ectively mercurous and mercuric salts. 

Mercuric Oxide, HgO, Red Precipitate, can be obtained 
by keeping mercury for some time at its boiling-point, also by 
heating mercuric nitrate. It is a red or yellowish-red powder, 
decomposed at a dull red heat. It is an active base, and dis- 
solves very slightly in water. It is used in medicine. When 
caustic soda is added to a mercuric solution, mercuric hydrate, 
Hgll202, is thrown down as a yellow precipitate. 

Mercuric Sulphate, HgSOi, is formed by boiling* mercury 
with sulphuric acid. The reaction is 

Hg + 2H,S0, = HgSO, + 2H,0 + SO,, 

similar to that with copper. Mercuric sulphate is a white 
j)owder, which is decomposed by water, forming a yellow 
oxysulphate, HgSOi + 2IIgO, called turpeth mineral. 

Mercuric Nitrate, HgCIs^Oa),, is generally seen in solution 
with excess of nitric acid, forming the acid mercury nitrate 
used in medicine. The normal salt is used as a source of the 
oxide. 

Mercuric Chloride, HgCl,, Corrosive Sublimate, is ob- 
tained by heating a mixture of mercuric sulphate and com- 
mon salt. 

HgSO, + 2NaCl = HgCL + Na,SO,. 

The mixture is strongly heated ; i\\Q mercuric chloride rises 
in vapor and condenses on a cool surface. This process is 
called sublimation. Corrosive sublimate is a heavy, white, 
crystalline powder, soluble in water and ether, and having 
an acrid metallic taste. It is extremely poisonous, about five 
grains being a fatal dose. It forms with albumen an insolu- 
ble precipitate. 

Mercuric Iodide, Hgl,, Red Iodide, is formed by mixing 
corrosive sublimate with potassium iodide. 



ELEMENTS OF CHEMISTRY. 165 

HgCl^ + 2KI = Hgl^ + 2KC1. 

Mercuric iodide is at first yellow, but rapidly changes to a 
brilliant scarlet. It is soluble both in HgCl2 and KI, and 
the solutions are used as tests for ammonia and various or- 
ganic principles. 

Mercuric Sulphide , HgS, Vermilion, is found as a red min- 
eral, cinnabar, an important ore of mercury. It can be pre- 
pared by passing hydrogen sulphide into mercury chloride. 

HgCl^ + H,S = HgS + 2HC1. 

Thus prepared it is black, but is converted into the red form 
by heating. It is used as a bright red paint; 

The Mercurous Salts are mostly of little importance. 

MercuTous Oxide, IIg20, is a black powder, easily decom- 
posed, obtained by the action of alkaline hydrates upon 
calomel. 

Mercurous Chloride, Hg2Cl2, Calomel, is formed similarly to 
corrosive sublimate, substituting mercurous sulphate for mer- 
curic. 

Hg^SO, + 2NaCl = Hg.Cl, + Na2S0,. 

The calomel is driven out by heat, and forms a sublimate. 
It is a white, heavy, tasteless powder, insoluble in w^ater. 

Mercurous Sulphate, IIg2S04, may be made by rubbing 
mercuric sulphate with another atomic proportion of mer- 
cury, 

Hg + HgSO, = Hg,SO,. 

Tests. Mercury imparts no characteristic color to flame. 
The precipitation tests are different for the two series of salts. 
Mercurous salts give wdth hydrochloric acid a white precipi- 
tate which is blackened by ammonia. Mercuric salts give 
with potassium iodide a yellow precipitate of Hgis, changing 
to scarlet and soluble in excess of the precipitant. 



166 ELEMENTS OF CHEMISTRY, 

Any compound containing mercury will give with Keinsch's 
test (g. V,) a bright silvery coating on copper foil ; also, with 
hydrogen sulphide in excess a black precipitate. • 



Zinc Group. This includes zinc, magnesium, cadmium 
and beryllium. They are never found free, but are tolerably 
easily reduced from their compounds. They each form but 
one definite oxide, which is insoluble in w^ater, not caustic, 
but capable of forming w^ell-marked. salts. Beryllium is 
somewhat uncertain in its relations. ♦ 

ZINC, Zn, eS. 

Sources. Zinc exists rather abundantly as sulphide 
(blende), carbonate (calamine), silicate (electric calamine) 
and as oxide. Zinc w^as known in the thirteenth century. 

Preparation. The ores are first converted into oxide by 
roasting in the air, and the oxide is then heated with char- 
coal in an earthen retort or crucible so arranged that the zinc 
may distil into a receiver. 

Properties. Zinc is hard, bluish-white, generally decid- 
edly crystalline. Sp. gr. 7.14. It melts at 770^ F. (410° C), 
and distils at about a red heat. It is brittle at ordinary tem- 
peratures, but becomes soft and malleable at between 212° 
and 302° F. (100° and 150° C), and at a higher tempera- 
ture again becomes brittle. Zinc oxidizes slightly in moist 
air, and when highly heated burns with a greenish-white 
flame, producing ZnO. Acids and strong alkalies dissolve it. 
The uses of it are numerous. It is employed in making sev- 
eral important alloys, as brass and gun-metal, w^hich contain 
copper and zinc, and German silver, which contains copper, 
zinc and nickel. Galvanized iron is simply iron covered 
with a layer of zinc by dipping it in a bath of melted zinc. 
Commercial zinc is very likely to contain arsenic. 



ELEMENTS OF CHEMISTRY. 167 

Zinc Oxide, ZnO, Zinc White, is easily made by burning 
zinc. It is a soft powder, yellow when hot, white when cold. 
It is used as a paint, as an application in surgical dressings 
and as a face-powder. It dissolves easily in acids. 

Zinc Hydrate, ZnHoOg, is produced by adding ammonia to 
a solution of a zinc salt. It is a white precipitate, soluble in 
acids and alkalies. 

Zinc Sulphide, ZnS, occurs as a crystalline mineral called 
blende. It is produced artificially as a white gelatinous mass 
by action of hydrogen sulphide on alkaline solutions of zinc. 

Zinc Carbonate, ZnCOs, Calamine, exists as a mineral. 
When zinc sulphate and sodium carbonate are mixed, an 
oxy-salt, 

SZnCOs + 5ZnO + 6H,0, 

is thrown down. 

Zinc Sulphate, ZnSO^, White Vitriol, is made either by dis- 
solving zinc in sulphuric acid or by oxidizing the sulphide. 
It forms wdiite crystals having the formula ZnS04 + 7H2O. 
They are soluble in water, have an acid reaction and act as 
an emetic. 

• Zinc Chloride, ZnCls, is made by dissolving zinc scraps in 
hydrochloric acid. It forms white masses, which absorb water 
rapidly from the air {deliquesce^ and make a strong sokition. 
Zinc chloride is a powerful corrosive, coagulates albuminous 
matter, and is used as a preservative in anatomical prepara- 
tions, also as an application in dentistry. When a strong 
solution of zinc chloride is mixed with zinc oxide, the two 
combine and form a hard, white insoluble mass which is used 
as a filling for teeth. 

Zinc Phosphate, or rather Oxy-phosphate, made by mixing 
zinc oxide with phosphoric acid, and consisting of zinc phos- 
phate united with zinc oxide, has come into use lately as a 
substitute for the oxychloride in filling teeth. 

Tests. Zinc burns w^ith a flame which is a mixture of red 



168 ELEMENTS OF CHEMISTRY. 

and blue. The best liquid test depends on the fact that a 
white precipitate is thrown down by the action of hydrogen 
sulphide on alkaline solution of zinc salts. 



MAGNESIUM, Mg, 24. 

Sources. Magnesium occurs as carbonate (dolomite), 
silicate (talc and soapstone), also as hydrate and chloride. 
Most natural w^ater contains magnesium compounds. It w^as 
discovered by Davy in 1808. 

Preparation and Properties. It is obtained by heating 
the chloride with sodium. It is bright and malleable. Sp. 
gr. 1.74. When strongly heated in the air it burns with a 
very bright light, producing MgO. Magnesium compounds 
often cause hardness in w^ater similar to that produced by 
calcium salts. 

Magnesium Oxide, MgO, Magnesia, is usually obtained 
by heating the carbonate to redness. It is a light, white 
powder, very feebly soluble in water, and neutralizing acids. 
Magnesium hydrate is also known. 

Magnesium Carbonate, MgCOs, occurs as a mineral. It 
is usually obtained by adding sodium carbonate to magnesium 
sulphate. In this case an oxycarbonate is formed, which is 
known as magnesia alba. 

Magnesium Sulphate, MgSO^, Epsom Salt. This body 
is obtained on the large scale by the action of sulphuric acid 
upon natural magnesium carbonate and silicate. It forms 
colorless crystals, isomorphous (see page 172), with zinc sul- 
phate. As thus crystallized the salt has the composition 
MgSOi + 7II2O. It is very soluble in water. 

Magnesium Chloride, MgClg, resem^bles zinc chloride in 
some respects, but does not have the same corrosive action. 



. ELEMENTS OF CHEMISTRY. 169 

Tests. Magnesium gives no color to a gas flame ; with 
the electric spark it gives a green light. A mixture of am- 
monia, ammonium chloride and sodium phosphate is used as 
a test for magnesium, but it is not applicable until after all 
bodies except compounds of the potassium group are removed 
from the solution. 

Cadmium, Cd, 112, occurs in various zinc ores. It is ex- 
tracted in the same manner as zinc, and is silver- white and 
crystalline. Sp. gr. 8.6. It melts at 442° F. (228° C), and is 
nearly as volatile as mercury. It is easily dissolved by ordi- 
nary acids. Its salts are of little interest, except the sul- 
phide. CdS is obtained as an orange-yellow precipitate by 
passing hydrogen sulphide into a solution of cadmium. 

Beryllium, or Gludniim, Be, 9.4, occurs in beryl, emerald 
and a few other minerals. It is white and malleable. 
Specific gravity, 2.1. 

Thorium, Th, 231.5, was discovered by Berzelius in 1828 
in a silicate called thorite. 

Yttrium, Y, 92, was discovered by Gadolin in 1794, and 
Erbium, E, 169, was discovered by Mosander in 1843. They 
exist in a mineral called gadolinite, found at Ytterby, Swe- 
den. 

The last three elements have been so little studied on ac- 
count of their rarity that it is as yet not possible to classify 
them definitely. 



Iron Group. This includes aluminum, iron, manganese, 
nickel, cobalt and partly chromium. They are not found 
native except in small quantity. They form two sets of com- 
pounds, acting in one set as dyads and in the other as double 
tetrads. Several are capable of forming well-marked anhy- 
drides. Uranium, iridium and rhodium are also described 
in this connection, although their exact relations are not 
made out. 

15 



170 ELEMENTS OF CHEMISTRY, 



ALUMINUM, Al, 27.5. 

Sources. Aluminum is very abundant as silicate, con- 
stituting clay and many common rocks. Most building 
materials are mixtures of aluminum silicate with other 
silicates. It was discovered by Wohler in 1828. 

Preparation. By decomposing the chloride w^ith sodium 
and by several other methods. 

Properties. Aluminum is white and not very lustrous, 
malleable and ductile, sonorous and very light ; specific grav- 
ity, 2.6. It tarnishes slightly in the air, and dissolves rapidly 
in hydrochloric acid and in caustic alkalies, but not in nitric 
acid. It melts at 842° F. (450° C). Its alloys are very 
valuable; that Avith copper, aluminum bronze, has the color 
of gold and keeps well in the air. 

Aluminum forms but one series of compounds, which pos- 
sess strong analogies to the tetrad series of iron salts ; hence 
aluminum is regarded also as a tetrad. Like iron, it forms 
compounds by the joint action of two tetrad atoms, which 
act as a hexad, as explained on pages 29 and 31. 

Aluminum Oxide, AI2O3, occurs naturally as corundum, 
which, when crushed, constitutes emery ; finely crystallized, 
as the ruby and sapphire. It can be prepared by heating 
ammonia alum; it then forms a white pow^der. In all the 
anhydrous forms it is absolutely insoluble in water, and 
almost so in acids and alkalies. 

Aluminum Hydrate, AI2H6O6, is usually obtained by 
adding ammonia to a solution of the sulphate. 

Al2(S04)3 + 6AmH0 = 3 Am^SO, + Al^HeOe. 

This hydrate is a gelatinous Avhite mass, easily soluble in 
acids and alkalies, and has a strong affinity for organic 
matter ; with organic colors it forms precipitates called 
lakes. In the art of dyeing, alumina is used as a mor- 



ELEMENTS OF CHEMISTRY, 171 

dant — that is, a material to cause the color to adhere firmly 
to the fabric. 

Aluminum oxide appears to possess a property similar to 
phosphoric anhydride, P2O5, of forming hydrates with dif- 
ferent proportions of water : 

AI2O3 + H2O = MJ1,0^ Metalumina. 

AI2O3 + 3H2O = Al^HfiOe Orthalumina. 

These are found as minerals, the first known as diaspore, the 
second as gibbsite. 

Aluminum Sulphate, Al2(S04)3, is now largely manufac- 
tured for use in dyeing and in other operations. It is pre- 
pared either by the action of sulphuric acid upon clay nearly 
free from iron, or by the roasting of a mineral termed alum 
shale, which contains iron disulphide, FeSs, and aluminum 
silicate. The roasting converts the sulphur into sulphuric 
acid, which then forms aluminum sulphate and iron sulphate. 
These are dissolved in water and separated by crystallization. 
AI2 (804)3 usually forms a white crystalline mass having an 
acid reaction. 

Alum. The word *^ alum," like the term " alcohol," long 
applied to a single substance, has now come to refer to a 
group of substances characterized by similarity of composi- 
tion and chemical relations. The alums are a series of double 
sulphates. One kind of alum has the formula, 

A1,(S0,)3 + K2SO, + 24H2O. . 

The aluminum in this compound may be replaced by most 
of the elements of this group. The potassium may be re- 
placed by any element of its group, or by ammonium, 
giving a series of salts of which a few instances are ap- 
pended : 

AUCSOOs + K2SO, + 24H2O Potassium alum. 

CYim,\ + Na2S0, + 24H2O Sodio-chromic alum. 

Fe2(S04)3 + AmaSOi + 24H2O Ammonio-ferric alum. 



172 ELEMENTS OF CHEMISTRY, 

The particular point about these compounds is that they all 
contain the same amount of water of crystallization and all 
crystallize in octahedra. Bodies that are similar both in 
composition and in crystalline form are called isomorphous. 

Common Alum, Ammonia Alum, crystallizes in large clear 
octahedra, which dissolve easily in water, the solution being 
acid to test-paper and strongly astringent. 

When alum crystals are gently heated they swell up, lose 
their water of crystallization and fall to a soft white powder — 
burnt alum. 

Aluminum Chloride, AlaCle, is prepared by heating alumina 
and charcoal in a current of chlorine. 

Al.Os + 3C + 6C1 = SCO + Allele. 

Glass, Pottery and Porcelain. — These important articles 
are mixtures of various silicates, especially aluminum, calcium 

and sodium silicates. 

Colored glasses are produced by the use of various oxides. 
Ferrous oxide, FeO, produces a deep green (bottle glass), and 
manganese dioxide communicates a purple tint. It is diffi- 
cult to obtain materials entirely free from iron which give 
a green tinge ; for a colorless glass manganese dioxide is 
added. 

Pottery and earthenware are made of clay, moulded while 
wet and then baked at a temperature which renders it no 
longer plastic. The glaze is a fusible sodium silicate made 
from a mixture of sand and salt. Lead silicate is also used. 
Porcelain is a mixture of feldspar (aluminum and potassium 
silicate), sand and kaolin, a hydrated aluminum silicate. 
These, Yvhen mixed with water, moulded to shape and heated 
to a high temperature, form a porous ware called biscuit 
This is glazed by fusing on the surface various silicates* 

The colors on pottery and porcelain are mostly mixtures of 
sand and metallic oxides. 



ELEMENTS OF CHEMISTRY, 173 

Aluminum silicate exists in combination Avith other silicates 
in a large number of minerals. 

Tests. Aluminum compounds give no color to common 
flames. When intensely heated by electric sparks a number 
of tints, chiefly red and blue, are produced. The precipita- 
tion tests are not always satisfactory. Ammonium hydrate 
throws down a gelatinous precipitate of aluminum hydrate. 



IRON, Fe, Be, 

Sources. Iron occurs very abundantly as oxide, sulphide 
and carbonate ; some of its compounds occur in small quan- 
tities in many rocks and soils, and hence it is dissolved by 
natural waters and taken up by plants ; from these sources it 
gets into the animal body, and is an essential constituent of the 
blood of the higher animals. Iron was known to the ancients. 
It sometimes occurs native, especially in meteoric stones. 

Preparation and Properties. The preparation of iron 
is a simple process of reduction. A fine-grade Quevenne's 
iron, for use in medicine, is made by passing hydrogen over 
sesquioxide. On the large scale, iron ore, which generally 
consists of an oxide or carbonate mixed with clay, sand and 
other minerals, is heated in blast-furnaces with coal and lime- 
stone. The limestone makes a fusible calcium silicate, slag ; 
the coal takes the oxygen away from the iron. The melted 
mass is then run out into thick bars, forming ipig or cast iron, 
the most impure form, containing four or more per cent, of 
carbon, also phosphorus, sulphur, silicon and other bodies. 
The arrangement of a blast-furnace is sho\vn in section in the 
cut. The mixture of ore, limestone and coal is put in at the 
top, and as it descends the chemical changes occur and the 
melted iron collects in the lower part or crucible, c, d, e; the 
15* 



174 



ELEMENTS OF CHEMISTRY. 



slag floats on the iron, and is drawn off from time to time. 
The iron is run out by the opening between g and /. A blast 
of hot air is introduced at d. 




This crude iron is worked in a furnace in a current of air, 
by which the impurities, especially the carbon, are burnt out, 

and the iron becomes kss fusi- 
ble and much tougher, consti- 
tuting wrought iron. A section 
of the furnace is shown in the 
cut. The fuel is placed at a, 
and the material to be heated 
at d, d. The flame is thrown 
dow^n on the iron by the arched roof, for wdiich reason it is 
called a reverberatory furnace. 




ELEMENTS OF CHEMISTRY. 175 

Steel contains about one-half per. cent of carbon ; it is 
therefore intermediate in composition. Steel was formerly 
made by heating wrought iron with charcoal ; it is now made 
directly from cast iron by burning out a certain percentage 
of the carbon (Bessemer process). Pure iron is very soft, 
but is found in commerce with various impurities which give 
hardness and other special qualities to the iron ; carbon gives 
hardness and fusibility ; phosphorus and sulphur give fusibil- 
ity and great brittleness, and are very objectionable. Cast 
iron melts at about 3000^ F. (1649° C). Iron is strongly 
magnetic and not much affected by dry air, but is oxidized 
by moist air and easily dissolved by acids. It forms two series 
of salts— /errous, in which it is a dyad, and ferric, in which it 
is apparently a triad, but the formulse of the ferric compounds 
are generally doubled, and the iron is regarded as a double 
tetrad acting as a hexad. 

Dyad iron, Hexad iron, 

— Fe— =Fe— Fe= 

Ferrous salts are generally green ; ferric salts brown or 
red. 

Conversion of one Series of Iron Salts into the 

other. 

Ferrous salts are converted into ferric by oxidizing agents. 
As the ferric salts are written with double formulae, the reac- 
tion will always require two molecules of ferrous for one of 
ferric; thus: 

2FeO + 0=FeA. 
2FeC03 + =- Fe,03 + 2C0,. 

* As nitric acid gives up three atoms of oxygen as an oxi- 
dizing agent (page 116), it follows that in writing reactions 
in which it is used six molecules of the ferrous salt must be 
taken. 

To make a normal ferric salt we must add one-half as much 
of the negative element as the ferrous salt already contains ; 



176 ELEMENTS OF CHEMISTRY, 

that is, one molecule of the radicle for every two molecules 
of the ferrous salt. For instance, in making ferric chloride, 
if we take 6FeCl2 + 2HNO3, we will get an oxy chloride or 
oxynitrate. The complete reaction is 

6FeCl2 + 6HC1 + 215.^0, = SFe^Cle + 4H,0 + 2N0. 

Ferrous salts are formed from ferric by the action of re- 
ducing agents, especially nascent hydrogen or sulphurous 
acid. The nascent hydrogen is usually obtained by adding 
to the ferric salt a mixture of zinc and sulphuric acid. With 
ferric chloride the reaction would be 

Fe^Cle + H2 = 2Fea + 2HC1. 

With ferric sulphate we should have 

Fe,(SO03 + H, = 2FeS0, + H,SO,. 
Hydrogen sulphide will also reduce ferric salts : 

Fe^Cle + H^S = 2FeCl2 + 2HC1 + S. 

Ferrous Oxide, FeO, is difficult to obtain. Ferrous hydrate, 
FeH202, is formed as a white precipitate by the action of 
caustic alkali upon a ferrous salt. It immediately begins to 
change by absorbing oxygen, and becomes ferric oxide. 

Ferric Oxide, Fe203, Red Oxide, Sesquioxide, occurs fre- 
quently in small amounts in many minerals, and also as iron 
ore, called red hematite or specular iron. It may be prepared 
artificially by heating ferrous sulphate (2FeS04 = Fe203 + 
SO2 + SO3), and is the residue obtained in making Nord- 
hausen sulphuric acid. It is a soft red powder, difficult to 
dissolve in acids. The finer grades constitute rouge; the 
coarser, Venetian red and crocus, are used for paints. 

Ferric Hydrate, Fe2ll606, is easily formed by adding 
caustic alkali to a ferric salt. 

Fe2Cl6 + 6AmH0 = 6 AmCl + Fe2H606. 

Ferric hydrate is a soft brown mass, insoluble in water, but 



ELEMENTS OF CHEMISTRY. 177 

dissolving easily in acid. Its chief importance is as an antidote 
to arsenic, for which use it must be freshly prepared. Ordi- 
nary iron rust consists of impure ferric hydrate, and it also 
occurs in an impure condition as brown hematite, a very im- 
portant ore of iron. 

Magnetic Iron Oxide, FeOjFe^Os, a union of the two oxides, 
is found as a finely crystallized mineral and valuable ore of 
iron. . It can retain magnetism, and is occasionally found in 
a magnetized condition, constituting loadstone. 

Ferrous Sulphide, FeS, made by fusing iron with sulphur, 
is a dark slag-like mass, used as a source of hydrogen sul- 
phide. 

Iron Disidpliide, FeSa, Iron Pyrites, is abundant as a min- 
eral, crystallized in brass-colored cubes often mistaken for 
gold, and hence called fool's gold. It is of no use as an iron 
ore, on account of the sulphur, but is used as a source of sul- 
phuric acid and some sulphates. 

Ferrous Carbonate is a mineral and valuable iron ore, and 
exists in many mineral (chalybeate) w^aters. It is produced 
by mixing ferrous sulphate with sodium carbonate. 

FeSO, + Na^COs =- FeCOg + Na.SO^. 

In this form, however, and also as dissolved in water, it is 
prone to oxidation, passing into the condition of ferric hy- 
drate, which forms a red deposit. This oxidation is hindered 
by sugar, and a ferrous carbonate, known as Vallet's mass, is 
prepared for medical use by precipitating it in contact with 
sugar. The natural carbonate is permanent in the air. 

Ferric Carbonate has not been obtained. 

Ferrous Sidphate, FeSOi, Green Vitriol, Copperas, is formed 
by dissolving iron in sulphuric acid or by oxidizing iron py- 
rites. It forms clear green crystals containing FeSO^ + TH^O, 
easily soluble in w^ater, the solution being liable to oxidation. 



178 ELEMENTS OF CHEMISTRY, 

It is used in the manufacture of ink and in dyeing. The 
crystals effloresce on exposure to air. Ferrous sulphate is a 
reducing agent, and is called a disinfectant, but merely 
acts as a deodorizer by absorbing some sulphur compounds. 
It forms double salts with ammonium and potassium sul- 
phates. 

Ferric Sulphate, Fe2(S04)3, is made by heating together 
a mixture of ferrous sulphate, sulphuric acid and nitric acid. 
The reaction is 

6FeS0, + SH^SO, + 2HNO3 = SFe^CSO^s + 4H,0 ^-2N0. 

If one-half the above quantity of sulphuric acid be used, an 
oxysulphate, 5Fe2(S03)3 + FcaOs, is formed, called MonseVs 
Salt, or when dissolved MonseVs Solution, and used as a 
styptic. 

Ferric Chloride, FcsCle, is generally seen as an alcoholic 
solution called muriated tincture of iron. Ferric chloride 
is made either by dissolving ferric hydrate in hydrochloric 
acid, 

Fe^HeOe + 6HC1 = Fe.Cle + GH^O, 

or by boiling ferrous chloride with nitric and hydrochloric 
acid, 

6FeCl, + 6HC1 + 2HNO3 = SFe^Cle + 4S.,0 + 2N0. 

When the solution is evaporated a red crystalline mass of 
Fe^Cle + 6H2O is formed, which is decomposed by heat. The 
anhydrous salt is yellow, and extremely deliquescent. The 
solution dissolves ferric hydrate, forming a ferric oxychloride. 

Iron nitrates, iodides and bromides do not possess special 
interest. 

Tests. Iron gives no color to gas flames ; w^ith the elec- 
tric spark it gives a mixture of many tints. Ferrous salts 
are characterized by their green color, ferric by red or brown. 
The following are the principal liquid tests : 



ELEMENTS OF CHEMISTRY. 



179 







With Ferrous Salts. 


With Ferric Salts. 


Ammonia, 


Green ferrous hy- 
drate, turning red, 


Ked ferric hydrate. 


Potassium ferro- 
cyanide, 


Li^ht blue precipi- 
tate, 


Dark blue precipitate 
(Prussian blue). 


Potassium ferri- 
cyanide, 


Dark blue precipitate 
(TurnbulFs blue). 


No precipitate. 


Tannin, 


Ko action, 


Black precipitate. 


Potassium sul- 
phocyanate. 


No action, 


Blood-red color, but 
no precipitate. 









MANGANESE, Mn, SS, 

Sources. Manganese exists principally as oxide, also as 
sulphide, carbonate and silicate. It was discovered by Gahn 
in 1780. 

Preparation and Properties. By reducing the oxide or 
carbonate with charcoal, or by electrical decomposition of the 
chloride. It is grayish- Avhite, brittle and hard ; specific grav- 
ity between 7 and 8. It forms two series of salts parallel to 
those of iron. 

MaiiganouB Oxide, MnO, is obtained by igniting the car- 
bonate ; the hydrate, Mnll202, is obtained by adding an 
alkali to a manganous salt. Both substances absorb oxy- 
gen rapidly. 

Manganous Chloride, MnCJg, may be obtained from the resi- 
due left after the preparation of chlorine. It forms pink 
crystals, deliquescent and soluble in w^ater. 

Manganous Sidjohate^ MnSO^, is made by dissolving the 
oxide or carbonate in sulphuric acid. It is a rose-colored 
salt, soluble in water, and used in dyeing. It crystallizes 
with 7H2O. 



180 ELEMENTS OF CHEMISTRY. 

Manganese Dioxide, M11O2, Black Oxide, This is rather 
an abundant mineral, occurring crystallized or in masses. It 
is extensively used as an oxidizing agent and in the manufac- 
ture of chlorine. Ordinarily it is in black masses or powder. 
It conducts electricity and dissolves in acids with evolution 
of oxygen. When heated to redness it is converted into an 
intermediate oxide, MusO^. 

Manganic Oxide, Mn203, is found as a mineral. It is a 
weak base. 

Manganese Acids. Manganese is capable of forming 
two anhydrides, which are not known in the free state, but 
of which some of the salts are common. The acids are — 

H2Mn04 Manganic acid. 

H2Mn208 Permanganic acid. 

The former has not been obtained. 

Manganates. These are formed by fusing manganese diox- 
ide with caustic alkali and potassium nitrate or chlorate. In 
this way potassium manganate, K2Mn04, is formed as a green 
crystalline mass. When dissolved in water the manganates 
turn into permanganates by the following reaction : 

3K2Mn04 + 2H2O = K^Mn^Os + Mn02 + 4KH0. 

The change of composition is indicated by a change of color 
from green to red, for which reason the potassium manganate 
was called chameleon mineral. 

Potassium Permanganate, KaMugOg, is now made in 
large amount as an oxidizing and deodorizing agent. The 
solution slowly decomposes when exposed to the air, and is 
supposed to give off ozone, and thus act as a disinfectant. 
It is decomposed by organic matters, by sulphites and sul- 
phides and reducing agents generally, becoming converted 
into a colorless solution. It can therefore be employed not 
only to destroy organic matter, but also as a measure of the 
amount present. - 



ELEMENTS OF CHEMISTRY. 181 

Tests. Manganese compounds give to gas flame a mix- 
ture of yellow and green light. The principal test is the 
flesh-colored precipitate, MnS, produced by ammonium sul- 
phide. 



NICKEL, Ni, 59. 



Sources. Nickel occurs principally in union with arsenic 
and sulphur ; also in meteoric iron as an alloy. It was dis- 
covered by Cronstedt in 1751. 

Preparation. Nickel is reduced by roasting and reduc- 
tion with charcoal. 

Properties. It is hard and white, of specific gravity 8.8, 
fusing at a high temperature and resisting the action of air 
at common temperatures. Like iron, it can acquire perma- 
nent magnetism. Solution of nickel can be decomposed by an 
electric current, and nickel-plating is performed in this way. 
An alloy of copper, zinc and nickel is called German silver, 
and some other alloys have been used in coins. 

Nickel Monoxide, NiO, is obtained by heating the nitrate 
or carbonate. A hydrate, Nill202, is obtained in the usual 
manner. It is green and soluble in ammonia. Its com- 
pounds with acid are mostly bright green. 

Nickel Sesquioxide, Ni203, is also known, but does not 
appear to form salts. 

Nickel Sulphate, NiSO^, is the most important salt. It 
usually crystallizes with 7 molecules of water, and can easily 
form double salts with potassium and ammonium sulphates. 

Tests. Nickel compounds give no color to flame. They 
are characterized by bright green or blue color, and a green 
precipitate with potassium cyanide. 

Cobalt, Co, 59, discovered by Brandt in 1733, is found as- 
sociated with nickel, which it closely resembles in properties 
and chemical relations. Its compounds are mostly red or 

16 



182 ELEMENTS OF CHEMISTRY. 

blue. The element itself is hard, white, magnetic and dif- 
ficult to fuse ; specific gravity, 8.7. The oxides, sulphates, 
carbonates, etc. resemble in composition those of nickel. It 
produces with the electric spark a mixture of colors. The 
tests are nearly the same as those of nickel, the distinction 
being that potassium cyanide forms wdth cobalt salts a com- 
pound which is not so easily decomposed by acids as the cor- 
responding nickel compound. 



CHROMIUM, Cr. 52.2. 

Sources. Chromium occurs principally as an oxide in 
combination with iron oxide, constituting chrome iron ore, 
FeO,Cr203 ; also as lead chromate, PbCrO^. It was discov- 
ered by Vauquelin in 1797. 

Preparation and Properties. By heating the oxide 
W'ith charcoal, chromium is obtained as a hard crystalline 
mass', not easily oxidized or dissolved. It forms two sets of 
salts, analogous to those of iron, and also a marked anhy- 
dride, which forms salts isomorphous with the sulphates. 
By this fact chromium is partly related to the oxygen group. 
The compounds in which it acts as a positive metal are of 
very little importance ; they agree mostly with the corre- 
sponding iron and manganese compounds. The chromous 
salts are unstable. Almost all the chromium compounds are 
high-colored. 

Chromic Oxide, Chromium Sesquioxide, Cr203, Chrome Green, 
obtained by decomposing some of the chromates {q, v.), is a 
bright green powder used as a paint. 

Chromic Anhydride, CrOs, is easily obtained by the ac- 
tion of acids upon the chromates. It forms bright red crystals, 
very deliquescent, soluble in water and having powerful oxi- 
dizing properties. 



ELEMENTS OF CHEMISTRY. 183 

Chromates are formed by heating chrome iron ore with 
alkali and nitre. The most common salts are those of 
potassium. 

Potassium Chromate, K^CrO^, forms lemon-yellow crys- 
tals soluble in water. 

Potassium Anhydro chromate, K2Cr04Cr03, commonly known 
as bichromate, is in large, bright red crystals which are soluble 
in water. It is extensively used in dyeing and as a source of 
various colors. 

Lead Chromate, Chrome Yellow, PbCrO^, is easily formed 
by adding a soluble chromate to a lead salt. 

PbCNOs), + K^CrO, == PbCrO^ + 2KNO3. 

It is bright yellow and insoluble in water. An oxychromate, 
PbCrO^ + PbO, is known as a scarlet pigment. 

Chromates are decomposed when heated with organic matn 
ter, especially in the presence of an acid. The change of 
composition is generally indicated by a change of color from 
the yellow or red of the chromate to the green of the chromic 
salt. 

Exp. Add to a dilute solution of potassium anhydrochromate a few 
drops of alcohol and some hydrochloric acid, and boil the mixture for 
a few moments. Vapors of aldehyde (q. v.) will be given off; and the 
red color of the liquid will change to green, chromic chloride being 
formed. 

The reaction is, 

K^CrO.CrOs + 8HC1 = Cr^Cle + ^B.,0 + 2KC1 + O3. 

The O3 oxidizes the alcohol to aldehyde. 

A mixture of potassium anhydrochromate and sulphuric 
acid is used as an oxidizing agent in galvanic batteries. 
The chromic acid becomes reduced to sesquioxide, and forms 
chromic sulphate; the liquid turns green, and afterward 
deposits dark ruby-red crystals of chrome-alum. 

K2SO, + Cr,(S0,)3 + 24H,0. 



184 - ELEMENTS OF CHEMISTRY, 

Tests. Chromium compounds communicate no color to 
flame ; with the electric spark they give a mixture of green 
and dark blue. Chromous and chromic compounds are not 
often encountered in analysis, and are generally dbnverted 
into chromates, which are recognized by their color and the 
yellow precipitate of lead chromate formed when mixed with 
lead acetate. 

Rhodium, Eh, 104.3, discovered by WoUaston in 1803, 
exists in platinum ores. It is hard and brittle, melting 
only at a high temperature, and then oxidizing. Specific 
gravity, 12.1. The atomicity of rhodium seems to resemble 
that of iron ; it forms a monoxide and sesquioxide. 

Iridium, Ir, 198, discovered by Tennant in 1803, is found 
with platinum and osmium. It is a hard, white, not very 
tough solid, which is difficult to fuse and to dissolve. It 
forms, like rhodium, compounds which recall those of iron. 
We have iridous chloride, IrCla, and iridic chloride, Ir2Cl6. 

Osmium, Os, 199, discovered by Tennant in 1803, is asso- 
ciated with platinum. It resembles platinum in many prop- 
erties, and has high lustre; specific gravity, 21.4; very diffi- 
cult to fuse, and forms an amalgam with mercury. Five 
oxides are known, OsO, OS2O3, OsO,,, OsOs, OsO^. The mon- 
oxide and sesquioxide form an imperfect series of salts ; the 
trioxide and tetroxide form salts with bases. 

Molybdenum, Mo, 96, discovered by Bergman in 1781, 
occurs chiefly as disulphide and as lead molybdate, both 
rather rare minerals. It forms three oxides, MoO, MoO., 
M0O3. The last, molyhdic anhydride, forms salts called 
molybdates. Ammonium molybdate, Am2Mo04, is used as a 
test for phosphoric acid, with which it forms a highly insol- 
uble yellow precipitate. 

Uranium, U, 120, was discovered by Klaproth in 1789. 
It is rather rare, occurring as oxide and phosphate. It is a 
grayish solid, not oxidized by air or water, but dissolving in 



ELEMENTS OF CHEMISTRY. 185 

acids. It forms two classes of compounds, uranous (tetrad) 
and uranic (hexad). Uranic oxide, UO3 can act as an anhy- 
dride, forming uranates. Uranium compounds are generally 
yellow or yellowish-green, and are fluorescent ; that is, shine 
brilliantly under the influence of rays of light to which the 
eye is ordinarily not sensitive. Glass colored yellowish with 
uranium oxide is much used in optical experiments. 

The following elements are not yet definitely classified, but 
are probably related to aluminum : 

Cerium, Ce, Lanthanum, La, and Didymium, Di, occur 
together in a few rare minerals. They form oxides which are 
analogous to alumina, and highly insoluble oxalates. Solu- 
tions of didymium salts when examined by the spectroscope 
show several absorption bands ; that is, points at which the 
light is interrupted. 

Indium, In, 1 1 3.4, exists in ores of zinc obtained at Frei- 
berg, Saxony. It w^as discovered in 1863 by Eeich and Rich- 
ter. It gives when heated a violet-blue flame, which is a mix- 
ture of indigo and blue. 

Gallium, Ga, 68.9, exists in small quantities in various 
zinc ores. It has only been obtained in small quantity. It 
was discovered by Lecoq de Boisbaudran in 1875. Gallium 
melts at 86° F. (30'' C), and will therefore melt by the heat 
of the hand. 
16* 



ORGANIC CHEMISTRY. 



Organic Bodies were at first understood to be those that 
exist only in living structures. The progress of chemistry 
made known many substances which could be produced by 
artificial means from the true organic bodies, and thus or- 
ganic chemistry came to include not only the constituents of 
animals and plants, but the derivatives from them. A still 
further advance was made when some of these substances 
were produced directly from their elements without the in- 
tervention of life, thus showing that inorganic and organic 
bodies were not essentially different. Attempts have been 
made of late years to dispense with the separate consider* 
ation of organic bodies, and to include their description 
under the title " Carbon Compounds," on account of the 
almost invariable presence in them of that element. The 
method has not reached general acceptance, and to follow 
it at present would be of doubtful scientific advantage ; and 
although the essential distinction between the two branches 
of the science has faded away, it is still convenient to de- 
scribe under one section a great many bodies which can be 
made artificially, but which are generally derived from 
organized tissues. These so-called organic bodies are dis- 
tinguished by a few peculiarities. The greater number of 
them contain carbon, hydrogen and oxygen. Some contain 
only carbon and hydrogen ; others contain nitrogen. The 
extensive variety of compounds is due to differences in pro- 
portion and arrangement of atoms. The organized tissues of 

J86 



ELEMENTS OF CHEMISTRY. 187 

plants and animals — muscle, brain, skin, seed, leaf, pollen, etc. 
— are generally complex in character, and often contain other 
elements, especially sulphur and phosphorus, in addition to 
those mentioned above. Many organic bodies are subject to 
change, and, as a rule, the more complex the substance, the 
more easily is it decomposed. 

Organic chemistry presents us with a large number of 
radicles. The most important of these are compounds of 
carbon and hydrogen. Their number is greatly increased 
by the power which the carbon possesses (at least this is the 
accepted theory) of combining with itself, forming duplicated 
atoms, or, as they have been called, carbon skeletons. In this 
manner we have 

- Carbon, tetrad. Dicarbon, hexad. Tricarbon, octad. 

I II III 

— c— — c— c— — c— c— c— 

I II III 

It will be noticed that the addition of each carbon atom adds 
two degrees to the atomicity, to saturate which two atoms of 
hydrogen will be required. It follows, therefore, that if we 
add CII2 to any radicle, w^e do not change its atomicity. In 
CH3, for instance, w^e have a monad radicle of which the 
graphic formula may be given — Cc::ill3 ; if to this we add 
=C=^Il2, we will get Ha^^C — C— II3, in which one bond is 

still unsatisfied. In accordance with this principle, we have 
a number of series, the members of which differ by CH2, and 
possess the atomicity of the lowest member. Such a series, 
differing by CII2, is said to be homologous. 

It is convenient to arrange organic compounds according 
to the radicles they are supposed to contain, although a great 
many bodies cannot yet be referred to known radicles. These 
latter will either be described apart or in connection with those 
of known composition that they most nearly resemble. 

The complexity of organic compounds is such that two 
bodies may have the same composition, but have only par- 



188 ELEMENTS OF CHEMISTRY. 

tial resemblance or even be entirely different in properties. 
This is called isomerism, and is generally explained by sup- 
posing that the atoms are differently arranged in the different 
bodies. The annexed cuts will serve to represent the general 
principle of this explanation. Each block is made up of 
the same number of squares. 








Sometimes the difference of properties is explained by the 
supposition that the number of atoms present in the one sub- 
stance is greater than in the other, although the proiwrtion 
between the different atoms is the same. Thus, the following 
compounds are known : 



CNCl 


gaseous. 


V>'2iN 2^12 


liquid. 


C3N3CI3 


solid. 



In these it will be seen that the percentage composition is 
the same. Bodies that are rela1;ed in this manner are called 
'polymers. 

Organic bodies, as they occur in nature, are generally mix- 
tures of several distinct substances which may be very differ- 
ent in properties. Common fats, for instance, are mixtures of 
three distinct fats ; common rosin contains at least two, and 
often three, substances. 

The separation of these bodies from each other is called 
PROXIMATE ANALYSIS, and the bodies so separated are called 
PROXIMATE PRINCIPLES. The number of organic compounds 
has been greatly increased by the action of chemical agents 
upon these natural proximate principles. The chief means 
of producing such changes are briefly described : 




ELEMENTS OF CHEMISTRY. 189 

(a) Action of Heat Heat usually decomposes 
organic substances, leaving a residue of carbon 
and producing a mixture of bodies — solid, liquid 
and gaseous. 

The general nature of tliis effect may be observed 
by placing some pieces of bituminous coal in a test- 
tube provided with a cork and glass jet, and heating 
to redness. The escaping gas is similar in composi- 
tion to common illuminating gas, but burns with a 
rather smoky flame on account of the tar present. 

(b) Action of Oxygen, Oxygen when acting at low tem- 
perature generally forms acids, either by direct union or by 
removing the hydrogen and taking its place. A mixture of 
potassium permanganate and caustic alkali is now much used 
as an oxidizing agent. 

(c) Action of Nitric Acid, This sometimes produces a sim- 
ple oxidation. Very often it removes hydrogen and adds 
NO2. Nitrous acid sometimes removes H3 and substi- 
tutes N. 

(d) Action of Chlorine, Chlorine generally removes hy- 
drogen, and takes its place, atom for atom. Bromine and 
iodine have the same action. 

This substituting action of nitric acid and halogens gives 
rise to a large series of compounds, organic in general rela- 
tions, but not existing in any living tissue. The substitution 
of NO2 gives us a series of nitro-compounds, and takes place 
in the proportion of one molecule of NO2 for each atom of 
H. Nascent hydrogen often removes the NO2, and brings 
the body back to its original condition. 

(e) Action of Dehydrating Agents, Dehydrating agents 
(bodies which have strong affinity for water) generally 
remove both hydrogen and oxygen from the organia com- 
pound in the proportion of two atoms of H to one of 
O (K,0). 



190 ELEMENTS OF CHEMISTRY. 

(/) So-called Natural Changes. These are fermenta- 
tion, PUTREFACTION and DECAY. Fermentation is a change 
produced in an organic body by the action of a decomposing 
nitrogenous body whereby it is reduced to a simpler form. 
Putrefaction is a change taking place, especially in nitrogen- 
ous bodies, merely under the influence of the ordinary con- 
ditions. Decay is a modified putrefaction in which oxidation 
occurs. 

The processes of fermentation and putrefaction are attended 
by the development of microscopic living organisms, which 
have of late years been extensively studied, and are by many 
supposed to be the cause of the changes. Pasteur believes that 
the organisms found in fermenting liquids grow and multiply 
at the expense of the fermenting body, and thus bring about 
the change. Liebig thought that the cause of the fermen- 
tation w^as that the decomposition going on in the nitrogen- 
ous body present is communicated, by contact, to the mole- 
cules of the other substances. These views have been ex- 
tensively discussed in connection with the now popular ideas 
that most fevers and contagious diseases are caused by living 
organisms and germs ; but the question really belongs to 
physiology and biology, and not to chemistry. 

A considerable number of substances — e. g. zinc chloride, 
carbolic acid, salicylic acid, kreasote, etc. — have the power 
to prevent fermentation or putrefaction, and are called 

ANTISEPTICS. 

Analysis of Organic Bodies. — The best general test for an 
organic substance is the action of heat, which usually causes 
decomposition, with evolution of smoky, strong-smelling va- 
pors, and leaves a residue of carbon 
which can be burned off by heating 
^^v^ strongly in the air. 

This test can be easily applied by lieating 
the substance on platinum-foil or a piece of 
porcelain, as shown in the cut. 




ELEMENTS OF CHEMISTRY, 191 

Sulphuric acid also produces a characteristic blackening, 
due to liberation of carbon. 

The presence of nitrogen is usually indicated by a very 
disagreeable odor on heating ; more surely by heating the 
body ^vith an alkali, by ^vhich ammonia is formed. The 
accurate analysis of organic bodies is performed by burning 
them completely in a current of oxygen, and collecting and 
weighing the carbon dioxide, water and nitrogen which are 
thus produced. This process gives tYio, percentage ov ultimate 
composition. 

A formula 'vvhich expresses merely the composition of the 
body, without exhibiting the known or supposed arrangement 
of the atoms, is called an empirical formula ; a ratioxal 
formula is one which shows the arrangement of the atoms. 
Butyric acid and acetic ether are represented by the same 
empirical formula, C4E[g02, but their rational formulas show 
their complete difference : 

C2H5C2H3O2 Ethyl acetate (acetic ether). 
HCiH702 Hydrogen butyrate (butyric acid). 

Proximate organic analysis, or the sej)aration of the 
bodies existing in a mixture, is a matter entirely dependent 
on the nature of the substances present ; it is sometimes very 
easy, and in other cases so difficult as to be practically im- 
possible. Solids are generally separated by differences of 
solubility in water, alcohol, ether and other solvents ; liquids 
are separated by fractional distillation, in which advantage is 
taken of different boiling-points. Gases are separated by 
different absorbents. The principle of these methods may be 
illustrated by making a mixture of starch, sugar, rosin and 
some volatile oil. By gently heating the mixture the oil may 
be distilled off; cold water will take up the sugar, and hot 
water the starch ; alcohol Avill then dissolve the rosin. 



192 ELEMENTS OF CHEMISTRY. 



NOMENCLATURE OF ORGANIC BODIES. 

Great difSculty has been found in the nomenclature of 
organic bodies, and many have been given arbitrary names 
derived from fanciful relations or peculiarities. A large 
number of proximate principles are named from the articles 
from which they are extracted. The sugar in milk is called 
lactose, from lac, " milk ;" the active principle of tobacco is 
called nicotina, from nicotiana, the botanical name of the 
tobacco, etc. 

A large number of organic bodies may be regarded as 
made up of positive and negative radicles, in the same man- 
ner as inorganic bodies are made up of positive and negative 
elements ; and by assigning names to these radicles we form 
the names of the compounds into wdiich they enter, just as 
w^e form the names of inorganic compounds. When the 
compound contains an acid radicle, the syllable " ate " is 
used. 

In all cases in which a body has been formed by substitu- 
tion of one element or molecule for another, we may easily 
indicate the fact by attaching the name of the substituting 
body, and using the prefixes mono, di, tee, etc. to show the 
amount. To indicate the substitution of the molecule NO2, 
the word nitro is used ; to indicate the substitution of N for 
H3, the word azo is used. 

The application of these principles wdll be shown in the 
following pages. 

Classification of Organic Bodies. In the following 
pages the substances described wall, as far as possible, be 
arranged according to the radicles supposed to be present, 
beginning, as in inorganic chemistry, with the monads, and 
proceeding to those of higher atomicity. 



ELEMENTS OF CHEMISTRY. 



193 



ORGANIC BODIES NOT CONTAINING 
NITROGEN. 

Hydrocarbons and Derivatives. — Bodies consisting only 
of hydrogen and carbon are called hydrocarbons. Many of 
these are produced by the destructive distillation of organic 
substances, especially coal and wood. They are arranged in 
a number of homologous series, of which only the more im- 
portant will be given. The fusing- and boiling-points grad- 
ually rise as the number of carbon atoms increases, so that if 
the lower members are gases, those in the middle of the series 
will be liquids, the higher members will be solids. In each 
series the atomicity is determined by that of the first member, 
because, as explained above, the addition of CH2 does not 
affect the saturation. 

The series begins with CH^, which, being saturated, has 
no disposition to combine, and therefore is not truly a radicle. 
By successive subtractions of hydrogen we get radicles of in- 
creasing atomicity. The following table shows this fact, and 
also shows the system of nomenclature : 

(Saturated.) (Monad.) (Dyad.) (Triad.) 



Methane 
CH, 


methyl 
CH3 


methene 
CH2 


methenyl 
CH 




Ethane 
G2H6 


ethyl 
C2H5 


ethene 


ethenyl 
C2H3 


ethine 
C2H2 


Propane 
CsHg 


propyl 
C3H7 


propene 
CsHe 


propenyl 
C3H5 


propine 
CsHi 


Butane 
C4H10 


butyl 
C4H9 


butene 
CiHs 


butenyl 
C,H, 


butine 
QHe 


Quintane 
C5H12 


quintyl 
C5H11 


quintene 


quintenyl 
C5H9 


qui n tine 
C5H10 



The gradual diminution of hydrogen is indicated by the 
change of vowel in regular order ; those containing uneven 
numbers of hydrogen have, in addition, the syllable ''yl" 
17 



194 ELEMENTS OF CHEMISTRY, 

The atoms of carbon are (except in the first four, which 
have arbitrary names) indicated by the syllable taken from 
Greek or Latin numerals. 

Series dififering by H2, but containing the same number of 
carbon atoms, are called isologous. Thus C.sHg, C3H6, C3H4, 
are isologous. 

1st Series, Methanes, often called PxIraffins. These be- 
gin with CH4, and being saturated bodies they are compara- 
tively indifierent to chemical reagents. 

Marsh Gas, or Methane, CH4, is produced by distillation of 
wood and coal or by decay of vegetable matter. It is, next to 
hydrogen, the lightest body known. It exists in coal gas. 

Common Paraffin exists in petroleum and in coal-tar. It is 
a mixture of several of the higher members of the series. It 
is a white, waxy solid, easily fusible, little acted on by acids 
or alkalies, and used for a protecting coating in chemical ap- 
paratus. Cosmoline and its imitations are also in part soft 
paraffins. 

2d Series, Methyls. These begin with methyl, CII3, and 
are a series of monad radicles, forming the monatomic alco- 
hols. 

Some of the important members of the series are here 
given : 

CHb Methyl. C3H, Propyl. 

C2H5 Ethyl. ^ CJl, Butyl. 

CsHii Amyl, or Quintyl. 

These form compounds analogous in stru'cture, but not in appear- 
ance or general properties. The compounds are very important. We 
have — 

1. Normal oxides, called simpile etheks : 

(0113)20 Methyl ether, analogous to ISia20, sodium oxide. 
(C2H5)20 Ethyl ether 

2. Compounds with halogens, sometimes called ethers : 
(CH3)C1 Methyl chloride, analogous to ISTaCl, sodium chloride. 
(CsHiJCl Amyl chloride, 



ELEMENTS OF CHEMISTRY. 195 

3. Compounds analogous to salts, called compound ether? : 
(CH3)2S04 Methyl sulphate, analogous to Na^SO^, sodium sulphate. 
(C5Hii)N03 Arayl nitrate, " NaNOs, '' nitrate. 

4. Compounds analogous to the acid salts, called yinic acids : 

(CaHsJHSO^ Sulph-ethylic acid, analogous to KHSO^. 

(C^HiiJHSO, Sulph-amylic acid, 

5. Compounds analogous to the hydrates, called alcohols : 

(C,H5)H0 Ethyl alcohol, analogous to KHO. 

(C5Hn)H0 Amyl alcohol, 

6. Compounds containing two different radicles, analogous to the 
mixed salts and called mixed etheks: 

(CH3)(C2H5)0 Methyl-ethyl ether. 

Derivatives from the Second Series of Radicles. — 

Some of the derivatives from this series have been knovrn in 
more or less impure form for centuries ; one of them, common 
alcohol, being the active agent in intoxicating liquors, the use 
of which in one form or other dates from remote antiquity. 
The term alcohol is now extended to all the hydrates of posi- 
tive radicles. 

Methyl Alcohol, Wood Spirit, (CH3)H0, Methyl Hydrate, is 
usually made by distilling wood. The crude material is dif- 
ficult to purify. Pure methyl alcohol is colorless and of 
pleasant odor. It boils at 152° F. (66.5° C), and its effects 
on the animal system appear to be less severe and more 
transient than those of common alcohol. The methylated 
spirit of English chemists is a mixture of 90 parts common 
alcohol with 10 parts methyl alcohol. 

Ethyl Alcohol, Common Alcohol, Sjyirit of Wine, (CvH5)H0, 
Ethyl Hydrate, is produced in the vinous fermentation of 
sugar ; alcohol and carbonic anhydride being chiefly formed : 
it can also be prepared artificially. On the large scale the 
sprouted grain called malt is generally used. The general 
nature of fermentation will be explained in connection with 
the sugars. The fermented spirit, having a lower boiling-point 
than water, is concentrated by distillation, but the strongest 



196 ELEMENTS OF CHEMISTRY, 

spirit thus prepared contains 10 per cent, of water. To withdraw 
all the water, it is necessary to distil wdth quicklime, by which 
absolute alcohol is formed. This is very inflammable, greedily 
absorbs moisture, and mixes with water in all proportions. 

Proof spirit contains 50.8 parts by weight of alcohol to 
49.2 of water, and has a specific gravity of 0.920. Commer- 
cial alcohol is a colorless, volatile liquid, of which the prop- 
erties, eflects and uses are well known. The strongest spirit 
ordinarily furnished is about 95 per cent., and boils at about 
180° F. (81° C). Alcohol is contained in wine, beer and 
spirits; essential oils, sugar or extracts are mixed with it 
as flavoring agents. Whiskey, brandy and other spirits con- 
tain from 40 to 50 per cent, of alcohol ; wines, from 17 (port 
and madeira) to 7 or 8 (hock and light clarets) per cent. ; 
porter and strong ale contain from 6 to 8 per cent. ; lager 
beer, about 4 per cent. The efiervescence of fermented 
liquids is due to the carbon dioxide which is produced with 
the alcohol, thus: 

Glucose, Alcohol, 

CeHi^Oe, breaks up i^to 2C2H6O + 2C0,. 

The carbon dioxide is retained by bottling the liquid before 
the fermentation is over. 

Amyl Alcohol, Fusel Oil, (CsHiOHO, Amyl hydrate, is a 
by-product in fermentation, and is found in raw spirits and 
new liquors. When pure it is a colorless, oily liquid, with a 
peculiar odor, a hot and acrid taste, and decidedly poisonous 
in its action. 

The alcohols derived from the higher radicles are mostly 
wax-like. 

Ether, Ethyl Oxide, (€2115)20, is made by the action of 
dehydrating agents, especially sulphuric acid, upon alcohol. 
It appears that acid ethylsulphate is first formed and then 
decomposed. 

Alcohol, Acid ethylsulphate, 

(C2H5)HO + H2SO, ^ (C2H5)HSO, + H2O. 



ELEMENTS OF CHEMISTRY. 197 

Another molecule of alcohol is then acted upon, thus : 

Eth-er, 
(C,H3)H0 + (C,H5)HS0, = H,SO, + (C^H^)^^ 

Ether is a colorless, very volatile liquid of distinct odor, boil- 
ing at 95° F. (35° C). Specific gravity, 0.713. Its vapor is 
inflammable and very heavy. It is a solvent for fats, fixed 
and volatile oils, resins and many other proximate principles. 
Methyl and amyl ethers are also known. 

Compound Ethers. The alcohol radicles replace the hydro- 
gen of acids and form bodies called compound ethers. It 
will be sufficient to enumerate a few of the most important. 
Many of these compound ethers are fragrant, and are used as 
flavoring materials or as substitutes for fruit-essences. 

Ethyl bromide, (C2ll5)Br, is used in medicine. Amyl ace- 
tate, butyrate and valerate are used as flavors. Amyl nitrite 
is used in medicine. Ethyl nitrate exists in sweet spirit of 
nitre. 

Aldehydes and Acids. When alcohols are oxidized by 
a limited amount of oxygen, two atoms of hydrogen are 
removed and no oxygen is added. When oxidized in a free 
supply of oxygen, an atom of oxygen takes the place of the 
removed hydrogen. The bodies produced in the first case are 
aldehydes ; in the second, acids. In this way Ave have 

(CH3)H0 + O -= CH,0 Methyl aldehyde. 

(CH3)H0 + O2 = CH2O, Formic acid. ' 

Thus each alcohol may be made to yield an aldehyde and an 
acid. The acids are very important, and are often called fat 
acids, many of them existing in common fats. They may be 
produced by the substitution of one atom of oxygen for two 
atoms of hydrogen in the alcohol. The removed hydrogen 
is converted into water by another atom of oxygen. Thus, 

Methyl Alcohol, Formic Acid, 
(CH3')H0 + O, == CH A + H,0. 

The acids formed from this series of radicles are monobasic; 

17* 



198 ELEMENTS OF CHEMISTRY. 

that is, only one atom of hydrogen is capable of being re- 
placed by a metal. They are therefore usually written with 
a single atom of hydrogen separate from the , rest ; formic 
acid, for instance, is written HCHO2. The following are 
some of these acids and their corresponding alcohols : 

Alcohol. Acid. 

Methyl alcohol, (CH3)H0, yields HCHO2, Formic acid. 
Ethyl " (C2H5)HO, " HC2H3O2, Acetic acid. 
Propyl " (CaHOHO, " HC3H5O2, Propionic acid. 
Butyl " (C4H9)HO, " HaH.O,, Butyric acid. 
Amyl " (C5Hn)H0, " HC5H9O2, Valeric acid. 

Only a few of this series of acids will need description. 

Formic Acid, HCHO2, exists as a secretion in some stinging 
animals and plants. It is a corrosive volatile liquid and acts 
as a reducing agent. 

Acetic Acid, HC2H3O2. This, in the dilute state, consti- 
tutes vinegar, which contains about 5 per cent, of the acid, 
and is usually made by oxidizing dilute alcohol in the pres- 
ence of a ferment. Acetic acid is also produced in the dis- 
tillation of wood. When pure, it is a colorless, corrosive 
liquid, solidifying at 62.6° F. (17^^ C), and boiling at 246° F. 
(119° C). This is glacial acetfc^cid. The more dilute forms 
are less active, and in vinegar its effects are quite mild. 

Acetates. Many of these are important. Potassium and 
sodium acetates are very deliquescent. 

Lead acetate, Pb(C2H30.i)2, Sugar of Lead, made by dis- 
solving lead«iOxide in acetic acid, forms white crystals soluble 
in water. The solution is capable of taking up more lead 
oxide, and forming an oxyacetate known as Goulard's extract. 

Cupric oxyacetate is a compound of copper acetate with 
copper hydrate, and is known as verdigris. 

Valeric Acid. This is obtained by the action of oxidiz- 
ing agents on amylic alcohol. It also exists in some plants. 



ELEMENTS OF CHEMISTRY, 199 

It is an oily liquid of disagreeable odor. Several of its salts 
are in extensive use in medicine. 

The higher members of this monobasic series are generally- 
insoluble in water and oily or fatty in appearance. 

Third Series, Olefins. These begin Avith C2H4, olefiant 
gas, ethylene, which is contained in coal gas, and can be made 
pure by the action of dehydrating agents on common alcohol. 
The olefins are dyads. The hydrates constitute the diatomic 
alcohols or glycols. These are not important. Ethene glycol^ 
(C2H4)H202, is the best known. It is a thick liquid, sweet 
and colorless. 

Acids from Glycol. Two series of these exist — one 
derived by the replacement of tivo atoms of hydrogen by one 
atom of oxygen, and the other by the replacement of four 
atoms of hydrogen by two atoms of oxygen. The first is the 
lactic acid series ; the second, the oxalic acid series. 

The following will show the relation between the two 
groups : 

Glycol. First oxidation. Second oxidation. 

C2H6O2 C2H4O3, Glycolic G2H2O4, Oxalic. 

CgHgOz CsHgOa, Lactic C3HA, Malonic. 

C4ll]o02 CiHgOg, Oxybutyric C4II6O4, Succinic. 

Each series is homologous, and carbonic acid, CIl2©3, may be 
regarded as the first member of the first series. 

Only a few of these acids need description. 

Lactic acidj IIC3H5O3, is contained in sour milk, and is 
formed from sugar during the so-called lactic fermentation. 
It may be prepared artificially. It is a syrupy liquid which 
forms soluble salts. 

Oxalic acid, II2C2O4, exists ready formed in the juices of 
some plants, as sour-sorrel and garden rhubarb. It is made 
artificially by the action of nitric acid on sugar or of caustic 
alkali on sawdust. It is sometimes a result of disease in the 
animal system. It occurs in colorless crystals which contain 



200 ELEMENTS OF CHEMISTRY. 

2H2O, and is soluble in water, very sour and highly poison- 
ous. Many of its salts are insoluble in water, especially 
calcium oxalate. Its decomposition with sulphuric acid is a 
convenient source of carbon monoxide (page 139). With the 
monads two oxalates are formed. Acid potassium oxalate, 
KHC2O4, occurs in the leaves of plants, and is called salt of 
sorrel. Calcium oxalate, CaCzO^, is occasionally formed in the 
kidneys. Ammonium oxalate, AmaCaO^, is used as a test. 

Succinic acid is produced from amber, a fossil resin, and 
exists in a few plants. It can also be made by the action of 
nitric acid upon most fats. 

Fourth Series, Methenyl Series. These are triad rad- 
icles, beginning with CH, methenyl, which forms (CH)Cl3, 
analogous to BiCls. 

The series may be regarded as forming the triatomic alco- 
hols or glycerins, 

(03115)11303, glycerin, is the best known of the series. It 
is obtained by the decomposition of fats. It does not oxidize 
or evaporate in the air, and has a solvent action next to that 
of water. Heated with strong nitric acid, it forms nitro- 
glycerin, C3ll5(N02)303 (strictly trinitro-glycerin), which is a 
violent explosive, and when mixed with sand or other mate- 
rial constitutes dynamite. 

Chloroform, CHCI3, can be obtained by the action of chlo- 
rine on marsh gas, but the commercial article is made by dis- 
tilling alcohol with bleaching-powder. The reaction is com- 
plicated, and the product is at first quite impure. When 
pure it is a colorless, fragrant liquid, very volatile, not easy 
to burn, insoluble in water and much heavier than that^ 
liquid. It boils at 142^ F. (61° C). It has high solvent 
powers and is a valuable anaesthetic. 

Fats and Fixed Oils. These are compound ethers, 
mostly derived from jjropemjl, (C3H5), and therefore, like 
bismuth, requiring three molecules of a monobasic acid to 



ELEMENTS OF CHEMISTRY. 201 

form a normal salt. As found in the tissues of plants and 
animals, they are mixtures of several distinct bodies which 
can be separated by difference of melting-point, solubility, 
etc. The oils are merely fats with a low melting-point. 
They are usually divided into two classes : drying oils, which 
absorb gxygen from the air, and become hard and resinous, 
such as linseed and poppy oil ; non-drying oils, which remain 
fluid, as castor and sperm oil. Many fats and oils undergo 
partial decomposition in the air, producing a free acid ; this 
is called rancidity. 

Each distinct fat is usually called by a name derived from 
the acid that forms it. Glyceryl oleate is called olein; gly- 
ceryl stearate is called stearin. When caustic alkali is added 
to a fat, decomposition takes place ; soap and glycerin are 
produced. The reaction is analogous to that which occurs 
when bismuth nitrate is acted upon by an alkali. 

Bi(N03)3 + BKHO = BiHsOs + SKNOs. 

Stearin, Potass, stearate. Glycerin, 

(C3H5)(Ci8H350,)3 + 3KH0 = 3K(C,sH350,) + (CaH5)H303. 

Soaps produced by potassa are usually soft; those from 
soda, hard ; those made from other oxides are mostly insol- 
uble in water. This latter fact explains the curdling action 
of hard water. The calcium and magnesium salts produce 
insoluble soaps. When soluble soaps are treated with cold 
water they decompose into acid salt, Avhich precipitates and 
makes the soapsuds, and an oxy-salt, which dissolves and 
gives the cleansing action. 

A decomposition of the fats may be produced by the action 
of superheated steam. In this case glycerin and free acids 
are formed, and can be distilled ofl*. The process is used on 
the large scale. 

Stearin, Glycerin, Stearic acid, 

(C3H5)(C,8H350,)3 + 3H,0 = (C3H5)H303 + 3H(Cx8H350,). 



202 ELEMENTS OF CHEMISTRY, 

The acids of the fats may also be obtained by adding a 
strong acid to ordinary soaps. 

Of the higher series of hydrocarbons, the following are the 
most important : 

Benzenes. These begin with CgHe, benzene, benzole or 
coal-tar naphtha, which is the important member. 

Benzole or benzene is obtained by the fractional distillation 
of coal-tar and by the distillation of benzoic acid wdth lime. 
It is a colorless, volatile liquid, which solidifies at a little 
above the temperature of melting ice. Its solvent powers are 
very high, and it is lai-gely used for such purpose. Benzene 
must not be confounded with the mixture of hydrocarbons 
obtained by distilling coal oil and known as benzine. 

Nitrobenzole, oil of myrbane, C6H5(N02), is obtained by 
the action of strong nitric acid upon benzene : 

CeHe + HNO3 = CeHsCNO,) + H,0. 

The product is a yellow, oily liquid smelling like bitter 
almonds, insoluble in water and poisonous. It is important, 
because by the action of nascent hydrogen it yields aniline, 
from which many brilliant colors are made. 

Nitrobenzole, Aniline, 

C6H5(NO,) + He = (CeH5)H,N + 2H,0. 

Naphthalenes. — Naphthalene, CioHg, the only important 
member of the group, occurs in coal-tar. It is a w^hite, crys- 
talline solid, melting at 176^ F. (80° C), and slightly soluble 
in w^ater. 

Anthracenes. — Anthracene, CuHio, is obtained from coal- 
tar. It is especially valuable as a source of alizarine, the 
coloring-matter of madder. When pure it is a colorless solid, 
subliming at 212° F. (100° C), insoluble in water. 

Anthraquinone, Cull802, is obtained by the action of a 
powerful oxidizing agent, as chromic acid, upon anthracene: 



ELEMENTS OF CHEMISTRY. 203 

Anthraquinone is used as a source of artificial madder color. 
The process is, (a) the anthraquinone is heated with bromine : 

Dibromanthraquinone, 
CuHsO, + Br^ =-ChH6Bt,0, + 2HBr. 

(i) Dibromanthraquinone heated with potash gives potas- 
sium alizarate, from ^vhich the alizarine may be obtained by 
sulphuric acid. 

Potass, alizarate, 
CHH8Br,02 + 4KH0 = CuHeK^O, + 2KBr + 2H,0. 

Terpenes. These are principally natural products consti- 
tuting the volatile or essential oils, CsHe, called quintone, is 
the lowest member of the series know^n. 

Oil of Turpentine, CioHie, is obtained from turpentine, an 
exudation from pine trees, and consisting of resin and vola- 
tile oil. On being distilled, the volatile oil is collected in the 
receiver ; the resin remaining constitutes common rosin. Oil 
or spirits of turpentine is a thin, colorless liquid of peculiar 
odor. It is lighter than water, boils at 320° F. (160'' C.) 
and is a valuable solvent. It is partially oxidized in the air. 
Many fragrant oils obtained from plants have the same com- 
position, and are obtained by distillation. Some of these oils 
are — lemon, bergamot, coriander, hop, juniper and valerian. 
They are called essential oils — are mostly lighter than w^ater 
and freely soluble in alcohol and ether. 

Plants furnish us with a number of oxidized terpenes, 
among which are the camjjhors and resins. 

Common Camphor, CioHieO, obtained from the camphor 
laurel, is a white crystalline solid, volatile at ordinary tem- 
peratures. It is slightly soluble in water and freely in alco- 
hol and ether. 

Eeshis include a large group, of which many are true acids, 
and form salts constituting resin soaps. 

Common Rosin is the residue from the preparation of oil of 
turpentine. It is a mixture of two acids. 



204 



ELEMENTS OF CHEMISTRY. 



Lac, Copal and Mastich are familiar members of the group. 
As a class the resins are easily fusible, but not volatile ; in- 
soluble in water, but soluble in alcohol, which solution con- 
stitutes varnish. Gum-resins are simply mixtures of resin 
and gum ; oleoresins, mixtures of resin and volatile oil ; bal- 
sams contain benzoic or cinnamic acid. 

Caoutchouc and Gutta Fercha are terpen es found in the 
juices of plants. They are insoluble in water, but in the 
plants are usually in suspension, very finely divided, so as to 
make a milky liquid called an emulsion. Caoutchouc is 
elastic ; <=^utta percha is not. Both are capable of combining 
with sulphur to form peculiar and valuable compounds. The 
process is called vulcanizing. 



SUGARS AISID STARCHES. 

The sugars form an important group, the exact relations of 
which are not well understood, but they are generally regarded 
as alcohols or aldehydes derived from complex radicles. The 
group includes sugars proper, also gums, starches and wood- 
fibre. A remarkable similarity of composition and convert- 
ibility into one another by simple means is to be noted. The 
most important point in regard to their composition is that 
they contain oxygen and hydrogen in the proportion to form 
water. They are divided into three classes : 



1. SUCROSES 

(sugars proper). 

^12X122^^11 

Sucrose (Cane 

Sugar). 
Lactose (Milk 

Sugar). 



2. Glucoses 

(grape sugars). 
C6H12O6 

Dextrose (Grape 

Sugar). 
Lsevuiose (Fruit 

Sugar). 



3. Amyloses (starch 
and woody fibre). 

CeHioOs 
Starch. 
Dextrin. 
Inulin. 
Gum. 
Cellulose. 



Sucrose, or Cane Sugar, C12H22O11, exists in certain plants, 



ELEMENTS OF CHEMISTRY, 205 

especially sugar-cane and beet-root. It is extracted by press- 
ure ; the liquid is then boiled down carefully, the raw prod- 
uct decolorized by animal charcoal and finally crystallized. 
It is soluble in about twice its weight of cold water. When 
heated to about 420° F. (216° C.) a caramel is formed. 

Lactose, or Milh Sugar, is found only in milk. It is con- 
verted by dilute acids into a peculiar variety of glucose, and 
in the presence of cheese undergoes lactic fermentation. 

Glucose, or Grape Sugar, CeHisOe, is found in manna and 
honey and many kinds of fruits. It is a normal constituent 
of the blood, and is excreted in considerable amount in the 
disease called diabetes mellitus. 

Glucose presents tw^o modifications, dextrose and l^evulose, 
distinguished by their action on light. Dextrose may be 
obtained by boiling starch with dilute sulphuric acid, add- 
ing chalk and evaporating the liquid. It is soluble in dilute 
alcohol, but is not so sw^eet as sucrose. When a solution of 
cane sugar is boiled wdth dilute acids, a mixture of dextrose 
and Isevulose is formed, called inverted sugar, Lsevulose does 
not crystallize, and is sweeter than dextrose. 

Starch, CgHioOi, occurs in many plants. It is a w^hite pow^- 
der, which is made up of granules of various sizes having a 
definite organized structure. (The annexed 
cut shows a magnified view of the cells of the 
potato, with the starch granules in position.) 
These granules are not soluble in cold water, 
ether or alcohol, but if heated with water to 
about 160° F. (72° C.) they swell and break 
up, yielding a thick mass termed starch paste. 
Upon boiling this mass with more w^ater, the 
particles are reduced to so fine a state of division that they 
^Yill pass through a filter, and when the boiling is continued 
for some time the solution becomes clear and the starch solu- 
ble. The test for starch is the formation of a deep blue color 
with free iodine. Starch exists in the seeds of grasses, asso- 

18 




206 ELEMENTS OF CHEMISTRY. 

elated with an albuminous substance, diastase, which has the 
power to transform the starch into glucose. When the seed 
germinates this transformation begins, and if the germination 
be interrupted before the sugar begins to undergo further 
change, we have malt, which is simply sprouted grain, espe- 
cially barley. When malt is steeped in water and yeast 
added, the fermentation of the sugar begins. Dilute sul- 
phuric acid acts like diastase. 

Dextrin, C6H10O5. This substance is also known as British 
gum, and may be obtained by heating starch to about 320° F. 
(160° C). The change is much more speedily effected by the 
addition of a little hydrochloric or nitric acid. Dextrin, to- 
gether with dextrose, is formed when malt extract acts upon 
starch. It is insoluble in alcohol, but very soluble in water, 
and is used as a mucilage. It is converted into glucose by 
heating with dilute acids. 

Gum Arabic is a natural exudation from many species of 
Acacia, It consists chiefly of arabic acid, C12H20O10, united 
with calcium and potassium. 

Cellulose, CeHioOs, is the colorless material of woody fibre. 
It is obtained nearly pure by boiling cotton wdth alkali. Cel- 
lulose is a white substance, which dissolves in an ammoniacal 
solution of cupric oxide, but is insoluble in w^ater, ether or 
alcohol. Strong sulphuric acid converts it either into a solu- 
ble substance like dextrin, or into an insoluble substance, 
giving a blue color with iodine. By dipping sheets of paper 
into strong sulphuric acid parchment paper is obtained. 

Gun- Cotton. When cotton is put into a mixture of equal 
volumes of strong nitric and sulphuric acids, no apparent 
change occurs, but after drying it is found to be exceed- 
ingly inflammable. A substitution product is here formed, 
termed trinitro-cellulose, in which NO2 replaces hydrogen, 
aH,(NO,)A. 

Collodion is formed by dissolving certain kinds of gun- 



ELEMENTS OF CHEMISTRY. 207 

cotton in a mixture of ether and alcohol. It is much em- 
ployed in photography and surgery. 

Mannite, C6Hy(HO)6 or CeHuOfi, is a sugar-like substance 
contained in manna, an exudation from many species of ash. 
When acted upon by nitric acid it forms a compound termed 
nitro-mannite, or mannite in which six atoms of hydrogen are 
replaced by NO2. 

The sugars and starches are reducing agents, but not very 
energetic. The action is generally increased by the presence 
of strong alkalies. The tests for them are mostly dependent 
upon their reducing action upon the salts of copper, silver, 
bismuth and mercury. Glucose is especially active. 

Moore's test depends on the fact that a solution of sugar 
becomes darker on being boiled with caustic alkali. 

Troimner's test is performed by adding to the suspected 
solution a few drops of copper sulphate and a considerable 
amount of caustic soda or potassa. If sugar be present, the 
application of heat wall cause the precipitation of orange-red 
cuprous oxide, CU2O. 

JBoettger's test is performed in the same w^ay, substituting 
bismuth oxynitrate for copper sulphate. A black precipitate 
of free bismuth is formed. The most accurate test is by 
fermentation and recognition of the alcohol. 

Glucosides. These occur in many plants, and on decom- 
position give rise to a glucose, together with other substances. 
Only a few need be mentioned. 

Amygdalin, C20H27NO11 + 3H2O, is found in bitter almonds. 
It forms white soluble crystals. By the action of water (H2O) 
upon the amygdalin and the albuminous substance termed 
synaptase or einulsin, contained in the bruised bitter almond, 
a species of fermentation is set up, in which hydride of ben- 
zioyl (CtHsO), hydrocyanic acid (HON), and glucose (CeHiaOe), 
are formed. 



208 ELEMENTS OF CHEMISTRY, 

Salicin, CisHigOy, is found in the pith of the poplar and 
willow. It crystallizes in white brilliant needles. It is solu- 
ble in water and alcohol, the solution having a strong bitter 
taste. It yields saligenin and glucose. 

Tannins or Tannic Acids are the astringent principles of 
plants. Different forms exist in different plants ; most of 
them yield, on treatment with acid, glucose and gallic acid. 
They form with gelatin an insoluble precipitate but little lia- 
ble to decomposition, and with ferric salts a dark precipitate 
which remains for a long time suspended in water. Upon the 
first of these reactions depends the process of manufacturing 
leather, and upon the second the formation of common inks. 

The source of common tannin is gall-nuts, excrescences 
formed on various plants by the punctures of an insect. 
Tannin is uncrystallizable, insoluble in pure ether, but dis- 
solved by water and alcohol. This form of tannin is ap- 
parently not a glucoside. It has the composition CuHioOg. 



FERMENTATION. 

This is a change which organic bodies, especially the sugars 
and starches, suffer under the influence of complicated sub- 
stances termed ferments, giving products differing according 
to the nature of the fermented body and of the ferment. 

The circumstances necessary for the action appear to be — 
(a) proper food, especially the ammoniacal salts and alkaline 
phosphates; (b) a temperature of from 60° to 100° F..(15° to 
40° C), since at other temperatures the vitality of the ferment 
is destroyed. 

Mention has been made on a previous page of the various 
theories as to the nature of fermentation. 

A so-called spontaneous fermentation takes place in wine, 



• ELEMENTS OF CHEMISTRY. 209 

beer, milk and other liquids. Those who accept Pasteur's 
view ascribe the action to the sporules or seeds of living 
bodies floating in the air. These, dropping into the liquid, 
propagate themselves, and during the act of growing evolve 
the products of fermentation. If the liquid be left in con- 
tact only with air which has been jDassed through a red-hot 
platinum tube, or if the air be filtered by passing it through 
cotton, fermentable liquids may be preserved for any length 
of time without undergoing change. 

The principal forms of fermentation are five : 

1. The vinous, producing chiefly alcohol, CoHgO, and car- 

bonic anhydride, CO2. 

2. The acetous, " " acetic acid, C.H.O.. 

3. The lactic, " " lactic acid, C3HA. 

4. The butyric, " " butyric acid, C.HsO^. 

5. The mucous, " " gum and mannite. 



ORGANIC ACIDS NOT REFERABLE TO ANY OF 
THE ABOVE SERIES. 

A great many organic acids are known, and referred to 
different incomplete series that cannot be here enumerated. 
It will be suflicient to mention some important acids and 
indicate their sources and properties : 

3Ialic acid, H.^G^H^Os, occurs in the juices of many plants, 
as apples, pears, mountain-ash berries and tobacco-leaves. It 
may be made artificially. It is crystalline, sour, soluble in 
water and alcohol. Its salts have very little importance. 

Tartaric acid, HoQHiOe. This is found in many plants, 
but especially in grapes, where it exists as acid potassium tar- 
trate, KHCiH^O^. This salt is somewhat soluble in water, 
but scarcely soluble in dilute alcohol, and hence in the man- 
ufacture of wine, as the fermentation advances, the quantity 
18* 



210 ELEMENTS OF CHEMISTRY. . 

of alcohol increases, and the acid potassium tartrate deposits 
as a red mass called argols. This, being dissolved in hot 
water and crystallized, gives cream of tartar (called very 
wrongly, by some writers, cremor tartar). 

Tartaric acid is a crystalline body, soluble in water and 
very sour. Its solution in water develops a fungous growth 
and decomposes. Several varieties of the acid are known. 

Acid potassium tartrate is a white crystalline body, very 
sour and not very soluble in cold water. It is used in effer- 
vescing powders. 

Potassium tartrate, K2C4H4O6, is called soluble tartar. 

Sodio-potassium tartrate, NaKC4H406j is known as Roclielle 
salt. 

Tartar emetic is described on page 131. 

Oitric acid, H3C6II5O7, is the acid of lemons and oranges, 
■ and is also found in some other fruits. It is a crystalline 
body, very sour and easily soluble in Avater. 

Oleic acid, IIC18H33O2, exists in most natural fats and non- 
drying oils. It is solid at 57° F. (14'' C). Above this tem- 
perature it is a clear liquid, lighter than water and insoluble in 
it, but soluble in alcohol and ether. Crude oleic acid, made 
by the decomposition of fats by steam, as mentioned on page 
200, is used in soap-making under the name of red oil. 

Benzoic acid, IIC7II5O2, is found in many resins, but chiefly 
in benzoin, by heating which the acid sublimes in white, 
pearly plates. Most of the salts formed by benzoic acid are 
soluble. 

Salicylic acid, IIC7II5O3, is formed by the oxidation of 
salicin, the bitter principle of the willow. It may also be 
made by acting upon sodium phenyl ate wdth carbon dioxide. 
Salicylic acid forms wdiite crystals not very soluble in cold 
W'ater, but rather soluble in hot water and in alcohol. It is 
now used largely as a medicine and antiseptic. 



ELEMENTS OF CHEMISTRY. 211 

The acid also occurs in the oil of wintergreeii, methyl salicy- 
late, CGH3)C:H50,. 

Carbolic acid, HC6H5O, is hardly a true acid, but is so 
called from a power of taking up bases and forming bodies 
like salts. It is preferably called phenol or phenylic alcohol. 
It exists in coal-tar, and can also be made by several pro- 
cesses. It forms colorless crystals ; is very deliquescent and 
soluble in water. It melts at 93^ F. (34^ C), and boils at 
370^ F. (187^ C). It has a peculiar odor, much like that 
of kreasote, which is a somewhat similar body obtained from 
wood-tar. Phenol, salicylic acid and benzoic acid are used 
as antiseptics, and possess the power to retard the develop- 
ment of many forms of microscopic life. 

Picric acid, or Tri-nitro phenol, C6H3(N02)30, is a yellow 
crystalline substance, very soluble in water, and is formed 
when nitric acid acts upon phenoL It may also be obtained 
when nitric acid acts upon many other substances, as the 
skin, for instance. In the arts it is employed as a dye for 
silk and wool. It is monobasic, and some of its salts are 
explosive. 

Gallic acid, IIC-II5O5, is obtained from tannin. It is used 
as an astringent. By heat it yields pyroyallin, QJ^^O^, some- 
times called pyrogallic acid, which has the property of 
absorbing oxygen rapidly when mixed w^ith a base, and is 
used as a test for oxygen and as a reducing agent in photog- 
raphy. 



ORGANIC BODIES CONTAINING NITROGEN. 

These may be roughly divided into three classes : 

1. Those derived from or containing cyanogen, CN. 

2. Those containing KO, in substitution forH, and called 
nitrO'Compounds. Such of these as are of importance are 



212 ELEMENTS OF CHEMISTRY, 

described in connection with the substances from which they 
are obtained. 

3. Those derived from ammonia, and called amines or 
amides. 



CYANOGEN AND DERIVATIVES. 

Cyanogen, CN, is produced when organic matter contain- 
ing nitrogen, such as leather scraps, is heated with an alkali, 
especially in the presence of iron. Cyanogen is a gas, but is 
of no importance in the free state. It is often represented by 
the symbol Cy (see page 147). 

Hydrogen cyanide, HCN, HydroGyanic or Prussic acid. 
This body is not an acid, although often called so. It is 
produced by the action of acids upon cyanides. It is an 
easily decomposed liquid of a rather pleasant odor, and 
intensely poisonous, a drop or two causing death almost 
instantaneously. It is used in medicine in a much diluted 
form. Hydrogen cyanide is produced in the fermentation 
of some glucosides. 

Potassium cyanide, KCN, can be made by passing nitrogen 
over a mixture of potassium carbonate and charcoal. 

K.COs + C, + N, = 2KCN + SCO. 

It is usually made from potassium ferrocyanide (g. v?). It is 
in white, fusible, deliquescent masses, and is a violent poison, 
probably because it easily furnishes HCN by the action of 
even feeble acids. It is extensively used in photography in 
order to dissolve the unaltered salts of silver, a double salt 
of potassium and silver resultmg (KCN + AgCN). It is 
also employed in silver and gold plating. 

The cyanides have a strong tendency to form double salts, 
and several of these are of much importance. 

Potassium ferrous cyanide, FeCy2 + ^KCy, usually called 



ELEMENTS OF CHEMISTRY, 213 

potassium ferrocyanide and written KiCjeFe, is formed by 
heating a mixture of nitrogenous organic matter, iron scraps 
and potassium carbonate, and treating the mass with water. 
The salt forms large lemon-yellow crystals, which are not 
poisonous. It is much used in dyeing under the name of 
yellow prussiate of potash. Oxidizing agents convert the 
ferrous cyanide into ferric, and produce a body called 

Potassium ferrie cyanide, FcaCye + 6KCy, commonly called 
potassium ferricyanide, or red prussiate of potash. It forms 
large ruby-red crystals, soluble in water and used in dyeing. 
From these double cyanides others may be obtained, espe- 
cially with iron. When ferrocyanide is added to a ferric 
salt, a blue precipitate of Prussian blue is formed; when 
ferricyanide is added to a ferrous salt, TurnbulFs blue is 
formed. 

Cyanogen forms several acids which have the same per- 
centage composition, but different formulae: 



HCNO 


Cyanic. 


H,C,N,0, 


Fulminic. 


HaC^NsOa 


Cyauuric. 



This is called a polymeric series. We have also a sulphur 
acid, HCNS, which forms sulphocyanates. 



AMINES AND AMIDES. 

Most of the members of the nitrogen group combine with 
the hydrocarbon- and acid- radicles, producing substances 
which may be compared to amine, H3N, or to ammonium 
compounds, and often having strong resemblance to these 
in general properties. They are, in fact, more conveniently 
studied by taking amine and ammonium chloride as types, 
and regarding the radicles present as substituting the hydro- 



214 



ELEMENTS OF CHEMISTRY. 



gen. They are named from the radicles present, with a prefix 
indicating the number of molecules, and with the name of the 
member of the nitrogen group. If referred to the type H3N, 
they are called amines; if to the type NH4CI, oniums. 



Amines. 




Oniuras. 


H,,N 


Amine. 


H4NCI Ammonium 
chloride. 


(C,H5)H,N 


Ethylamine. 


(C2H5)H3NC1 Ethyl ammoni- 
um chloride. 


(C2H5),HN 


Diethyl amine. 


(C2H5)2(CH3)HNC1 Methyl diethyl 
ammonium 
chloride. 


(C,H5),(CH3)N 


Methyl diethyl- 
amine. 




(C.H5)3P 


Triethyl phos- 
phine. 




(C,H,),-B 


Triethyl borine.- 


(C2H5)4PI Tetrethyl phos- 
phonium io- 
dide. 



It has also been found that bodies can be obtained with 
two, three and four atoms of nitrogen, phosphorus, etc., giv- 
ing rise to diamines, triamines and tetramines. 

(CgH^jH^Ng Ethene diamine (CgH^jHeNglg Etliene diammonium 

iodide. 

Arsenic forms with methyl a compound which is interesting 
from its remarkable properties, and because it was known for 
a long while before its composition was understood. This is 
arsen-dimethyl, As(CH3)2 (in the free state As2(CIl3)4). It is 
produced by distilling potassium acetate with arsenous anhy- 
dride. It was originally called hahodyl — a word derived from 
the Greek and referring to the disagreeable odor. It is highly 
poisonous, but yields an acid, H As (€113)202, w^hich is appar- 
ently non-poisonous, although containing over fifty per cent. 
As. 

Several amines exist ready formed in plants. Among these 
are Coiiia, CgHisN, the active principle of water-hemlock, and 
Nicotina, C10H14N2, the active principle of tobacco. 



ELEMENTS OF CHEMISTRY. 



215 



Natural Alkaloids. The medicinal virtues of plants are 
sometimes due to resins or volatile oils, but generally to nitro- 
genous bodies which are evidently related to the amines and 
oniums, but their exact nature is not made out. They are 
mostly insoluble in ^Yater, but soluble in alcohol. With acids 
they generally form crystalline salts, and are therefore called 
alkaloids. It will be sufficient to give a table showing the 
composition, sources and important properties of the more 
important : 



Alkaloids. 


Sources. 


Properties. 


Formulae. 


Conia 


- 
Water-hemlock 


Colorless liquid 


CsH,5N 


iSTicotina 


Tobacco 


Oily liquid 


CioHuNj 


Quinia 


Peruvian bark 


White crystals 


C20H24N2O2 


Cinchonia 


" 


a u 


C2„H2,N20 


Morphia 


Opium 


a (( 


CnHi^NOs 


Atropia 


Belladonna 


a (( 


CnH.,3N03 


Veratria 


Hellebore 


White powder 


a2H,2N20s 


Strvchnia 


N"ux vomica 


White crystals 


c,ji,;n,o. 


Caffeina 


Coffee and tea 


a a 


C3H10X4O2 


Urea, CH4N2O, is of animal origin. 



The fully-developed tissues and organs of animals are of 
such complicated composition that little information has been 
obtained in regard to them. They contain other elements be- 
sides those mentioned in the preceding compounds, sulphur, 
phosphorus and iron being the most important. 



216 



ELEMENTS OF CHEMISTRY. 



ATOMIC WEIGHTS, SYMBOLS AND ATOMI- 
CITIES. 





* 


>, 








>^ 






"o 


*« 


.S^^' 




"o 


*o 


O -J;^ 


a 


a 


"a 

q 


o S 


o 


t 


a 

o 


1^ 


s 


C& 


< 


^^ 


S 


^ 


< 


5^ 


Aluminum 


Al 


iv 


27 


Mercury 


Jig 


// 


200 


Antimony 


Sb 


/// V 


122 


Molybdenum 


Mo 


vi 


96 


Arsenic 


As 


/// V 


75 


Nickel 


Ni 


// 


59 


Barium 


• Ba 


// 


137 


Niobium 


Nb 


V 


94 


Beryllium 


Be 


// 


9.4 


Nitrogen 


N 


/// V 


14 


Bismuth 


Bi 


/// V 


210 


Osmium 


Os 


vi 


199 


Boron 


B 


/// 


11 


Oxygen 





// 


16 


Bromine 


Br 


/ 


80 


Palladium 


Pd 


// iv 


106.5 


Cadmium 


Cd 


// 


112 


Phosphorus 


P 


/// V 


31 


Cgesium 


Cs 


/ 


133 


Platinum 


Pt 


iv 


197.1 


Calcium 


Ca 


// 


40 


Potassium 


K 


/ 


39.1 


Carbon 


C 


iv 


12 


Khodium 


Rh 


// iv 


104.3 


Cerium 


Ce 


/// 


138 


Rubidium 


Rb 


/ 


85.4 


Chlorine 


CI 


/ 


35.4 


Ruthenium 


Ru 


// V 


104.4 


Chromium 


Cr 


iv 


52.2 


Selenium 


Se 


f/ iv vi 


79.5 


Cobalt 


Co 


// 


58.8 


Silicon 


Si 


iv 


28 


Copper 


Cu 


// 


63.4 


Silver 


Ag 


/ 


108 


Didymium 


Di 


/// 


144.8 


Sodium 


Na 


/ 


23 


Erbium 


E 




169 


Strontium 


Sr 


// 


87.5 


Fluorine 


F 


/ 


19 


Sulphur 


S 


// iv vi 


32 


Gallium 


Ga 




68.9 


Tantalum 


Ta 


iv 


182 


Gold 


Au 


/// V 


196.7 


Tellurium 


Te 


// iv vi 


129 


Hydrogen 


H 


/ 


1 


Thallium 


Tl 


/ /// 


204 


Indium 


In 


/// 


113.4 


Thorium 


Th 




231.5 


Iodine 


I 


/ 


127 


Tin 


Sn 


iv 


118 


Iridium 


Ir 


// iv 


198 


Titanium 


Ti 


iv 


50 


Iron 


Fe 


// iv 


56 


Tungsten 


W 


iv 


184 


Lanthanum 


La 


/// 


139 


Uranium 


U 


// 


120 


Lead 


Pb 


// 


207 


Vanadium 


V 


/// V 


51.3 


Lithium 


Li 


/ 


7 


Yttrium 


Y 


// 


92 


Magnesium 


Mg 


// 


24 


Zinc 


Zn 


// 


65 


Manganese 


Mn 


// iv 


55 


Zirconium 


Zr 


iv 


89.5 



ELEMENTS OF CHEMISTRY. 217 

THE METRIC SYSTEM. 

The Metric System is a decimal system of weights 

and measures, and derives its name from the meter which 

is the unit of the system. 

Note. — The metric system originated in France, and was finally- 
made obligatory in that country in 1841. In 1866 its use in the 
United States was authorized by Act of Congress. 

The length of the meter was intended to be one ten- 
millionth of the distance from the equator to either pole, 
measured at the level of the sea; but it is in reality a 
trifle less. 

The higher denominations of any measure, obtained by 
multiplication of the unit, are named by prefixing to the 
name of the unit of that measure, the Greek numerals 
Deka, 10, Hecto, 100, Kilo, 1000, or Myria, 10000. 

The lower denominations of any measure, obtained by 
division of the unit, are named by prefixing to the name 
of the unit of that measure, the hatin numerals Deci, -^y 
Centi, ^, or Milli, y^. 

ABBREVIATIONS. 
The name of each leading unit is abbreviated by 
writing its first letter after the number denoting the 
given quantity; 1 1.= 1 liter, 5 m. = 5 meters, etc. The 
Greek names of the higher orders of units are abbreviated 
in capitals; Hg. = Hektogram, Kg. = Kilogram, etc. 
The Latin names of the lower orders of units are abbre- 
viated in small letters; ds. = decistere, mm. = millimeter, 
etc. In square measure and cubic measure, sq. and cu. = 
square and cubic respectively; 5 sq. Dm. = 5 square 
Dekameters; 9 cu. dm. = 9 cubic decimeters. 



218 ELEMENTS OF CHEMISTRY. 

MEASURES OF LENGTH. 

The unit of length is the Meter. 

10 Millimeters = 1 Centimeter = .3937079 inches. 

10 Centimeters = 1 Decimeter = 3.937079 " 

10 Decimeters = 1 METER = 39.37079 '' 

10 Meters = 1 Dekameter = 393.7079 " 

10 Dekameters = 1 Hektometer = 3937.079 " 

10 Hektometers= 1 Kilometer = 39370.79 " 

10 Kilometers = 1 Myriameter = 393707.9 " 

Note. — The Meter is used in the same manner as our yard, and the 
Kilometer as our mile. 

MEASURES OF CAPACITY. 

DRY MEASURE. LIQUID MEASURE. 

10 Milliliters =1 Centiliter =0.6102cu.in. or 0.338 fl.oz. 

10 Centiliters =1 Deciliter =6.1022 " " 0.845 gi. 

10 Deciliters =1 MTER = 0.908 qt. "l.Omi\i. 

10 Liters =1 Dekaliter = 9.08 " "2.6417 gal. 

10 Dekaliters =1 Hektoliter= 2.8375 bu, "26.417 " 

10Hektoliters=lKiloliter =28.375" "264.17 " 

lOKiloliters =1 Myrialiter= 283.75 " "2641.7 '' 

MEASURES OF ^ATEIGHT. 
The unit of weight is the Gram. 
10 Milligrams = 1 Centigram = 0.1543 grains. 
10 Centigrams = 1 Decigram = 1.5432 " 
10 Decigrams = 1 GRAM = 15.432 " 
10 Grams = 1 Dekagram = 0.3527 oz. Avoir. 

10 Dekagrams = 1 Hektogram = 3.527 " 
10 Hektograms= 1 Kilogram = 2.2046 lb. 
10 Kilograms = 1 Myriagram = 22.046 " 
10 Myriagrams= 1 Quintal = 220.46 " 
10 Quintals = 1 Tonneau = 2204.6 " 



ELEMENTS OF CHEMISTRY, 



219 



CUBIC MEASURE. 



CUBIC INCHES. 

1 Cu. In. = 16.39 Cu. Centimeters 6 Cu. In.= 98.32 Cu. Centimeters. 

2 " =32.77 '' 7 '' =114.70 

3 " =49.16 " 8 '' =131.09 

4 " =65.54 " 9 " =147.47 

5 " =81.93 " 10 '' =163.86 





CUBIC 


FEET. 




ICu. Ft.= 28.32 Cu. 


Decimeters. 


6 Cu.Ft.= 169.89 Cu. 


Decimeters. 


2 " = 56.63 


li 


7 


'' =198.20 


li 


3 " = 84.95 . 


(I 


8 


" = 226.52 


u 


4 " =113.26 


u 


9 


" = 254.84 


iC 


5 " = 141.58 


u 


10 


" =283.15 


(( 



CUBIC YARDS. 



ICu. Yd.= .7645 Cu. Meters. 

2 " =1.5290 " 

3 " =2.2935 " 

4 " =3.0580 " 

5 " =3.8225 " 



6 Cu. Yd. = 4.5870 Cu. Meters. 

7 '' =5.3515 

8 " =6.1160 " 

9 '' =6.8806 " 
10 " =7.6451 " 



LIQUID MEASURE. 



1 0111 = 1.1831 Deciliters. 

2 " =2.3662 " 

1 Pint = 4.7325 Deciliters. 



1 Quart = 9.4650 Deciliters. 

2 " =1.8930 Liters. 



GILLS. 

3 Gills = 3.5493 Deciliters. 

4 " =4.7325 

PINTS. 

2 Pints = 9.4650 Deciliters. 
QUARTS. 

3 Quarts = 2.8395 Liters. 



4 " =3.7860 " 
GALLONS. 

1 Gallon = 3.786 Liters. 6 Gallons = 2.271 Dekaliters. 

2 " =7.572 '' 7 " =2.650 " 

3 " =1.135 Dekaliters. 8 '' =3.028 

4 " =1.514 " 9 " =3.407 " 
6 " =1.893 " 10 " =3.786 " 



220 



ELEMENTS OF CHEMISTRY, 



DRY MEASURE. 



1 Pint = 5,5067 Deciliters. 

1 Quart =1.1013 Liters. 

2 '' =2.2027 " 

3 '' =3.3040 " 

4 " =4.4054 " 

1 Peck = 8.8108 Liters. 

2 " = 1.7621 Dekaliters. 

1 Bushel = 3.524 Dekaliters. 

2 " =7.048 

3 *" =1.057 Hektoliters. 

4 " =1.409 

5 " =1.762 



PINTS. 

2 Pints = 1.1013 Liters. 
QUARTS. 

5 Quarts = 5.5067 Liters. 



6 " 


= 6.6081 " 


7 ^' 


= 7.7094 " 


8 " 


= 8.8108 " 


PECKS. 




3 Pecks 


= 2.6432 Dekaliters. 


4 " 


= 3.5243 " 


BUSHELS. 




!. 6 Bushels = 2.114 Hektoliters. 


7 " 


= 2.467 


:s. 8 " 


= 2.819 


9 " 


= 3.171 


10 " 


= 3.524 



AVOIRDUPOIS WEIGHT. 



1 Ounce 


j = 2.835D< 


skagrams. 


9 


2 " 


= ^671 


a 


10 


3 '' 


= 8.506 


a 


11 


4 " 


= 1.134 Hektograms. 


12 


5 " 


= 1.417 


a 


13 


6 " 


= 1.701 


cc 


14 


7 " 


= 1.984 


cc 


15 


8 " 


= 2.268 


cc 


16 



OUNCES. 

9 Ounces = 2.551 Hektograms. 



POUNDS. 

1 Pound = 4.5359 Hektograms. 6 Pounds = 

2 " =9.0718 " 7 " = 

3 '' = 1.3608 Kilograms. 8 " 

4 " =1.8144 " 9 " = 

5 " =2.2680 " 10 " = 



2.835 




3.119 




3.402 




3.685 




3.969 




4.252 




4.536 




: 2.7216 Kilograms. 


3.1751 


a 


3.6227 


cc 


4.0823 


cc 


4.5359 


cc 



2000" 



.9072 Tonneau. 



2240 



= 1.0160 Tonneaux. 



ELEMENTS OF CHEMISTRY, 221 







APOTHE 


.CARIES' 


WEI 

s. 


GHT. 




GRAIN 




1 Grain = 6.480 Centigrams 


11 Grains 


, = 7.1280 Decigrams. 


2 ' 


' = 1.296 Decigrams. 


12 


ii 


= 7.7760 


3 ' 


' =1.944 


a 


13 


ii 


= 8,4240 " 


4 ' 


' =2.592 


« 


14 


ii 


= 9.0720 " 


5 ' 


' =3.240 


u 


15 


ii 


= 9.7200 " 


6 ' 


' =3.888 


u 


16 


ii 


= 1.0368 Grams. 


7 ' 


^ =4.536 


ii 


17 


ii 


= 1.1016 " 


8 ^ 


' =5.184 


u 


18 


ii 


= 1.1664 " 


9 * 


* =5.832 


(t 


19 


ii 


= 1.2312 " 


10 ' 


' =; 6.480 


tc 


20 


ii 


= 1.2960 " 



SGRUPLKS. 
2 Scruples = 2.5920 Grams. 3 Scruples = 3.8879 Grams. 

DRACHMS. 
1 Drachm = 3.8879 Grams 5 Drachms= 1.9440 Dekagrams. 



2 " =7.7758 " 


6 


a 


= 2.3328 


3 " =1.1664 Dekagrams. 


7 


it 


= 2.7216 


4 " =1.5552 


8 


a 


= 3.1103 " 


OUNCKS. 




1 Ounce = 3.1103 Dekagrams. 


7 Ounces 


= 2.1772 Hektograms 


2 " =6.2206 " 


8 




= 2.4883 " 


3 " =9.3309 


9 




= 2.7993 " 


4 " = 1.2441 Hektograms. 


10 




= 3.1103 


5 " =1.5552 " 


11 




= 3.4214 " 


6 " =1.8662 " 


12 




= 3.7324 



POUNDS. 

1 Pound = 3.7324 Hektograms. 6 Pounds = 2.2394 Kilograms. 

2 " =7.4648 '' 7 " =2.6127 

3 " =1.1197 Kilograms. 8 " =2.9859 

4 " =1.4929 " 9 " =3.3592 

5 '' =1.8662 " 10 " =3.7324 " 

Note. — The Troy pound, ounce, and grain have the same values as in Apothecaries' 
Weight. 



222 



ELEMENTS OF CHEMISTRY. 



APOTHECARIES' LIQUID MEASURE. 



MINIMS. 

1 Minim = .0616 Milliliters. 6 Minims = .3697 Milliliters. 

2 " =.1232 " 7 " =.4313 " 

3 " =.1848 " 8 '' =.4930 " 

4 " =.2465 " 9 ^' =.5546 

5 " =.3081 " 10 " =.6162 " 

FLUID DRACHMS. 

1 Fl. Dr. = 3.6973 Milliliters. 5 Fl. Dr. = 1.8486 Centiliters. 

2 " =7.3946 " 6 " =2.2184 

3 " = 1.1092 Centiliters. 7 " =2.5881 " 

4 " =1.4789 " 8 " =2.9578 



FLUID OUNCES, 



1 Fl. Oz. = 2.9578 Centiliters. 



2 




= 5.9156 


a 


3 




= 8.8734 


u 


4 




= 1.1831 Deciliters. 


5 




= 1.4789 


a 


6 




= 1.7747 


(C 


7 




= 2.0705 


iC 


8 




= 2.3662 


a 



9 Fl. Oz. 


= 2.6620 Deciliters. 


10 " 


= 2.9578 




11 " 


= 3.2536 




12 " 


= 3.5494 




13 " 


= 3.8452 




14 '' 


= 4.1409 




15 " 


= 4.4367 




16 " 


= 4.7325 





1 Pint = 4.7325 Deciliters. 

2 '' =9.4650 

3 " =1.4197 Liters. 

4 " =1.8930 " 



PINTS. 



5 Pints = 2.3662 Liters. 

6 '' =2.8395 " 

7 " =3.3127 " 

8 " =3.7860 " 



GALLONS. 

1 GalIon= 3.786 Liters. 6 Gallons = 2.271 Dekaliters. 

2 " =7.572 " 7 '' =2.650 " 

3 " =1.135 Dekaliters. 8 '' =3.028 " 

4 '' =1.514 " 9 '' =3.407 " 

5 " =L893 " 10 " =3.786 « 



INDEX. 



A,U. 

Absorption bands, 185. 

Acetic acids, 198. 

Acids, 41-2, 87-8, fat, 200; prin- 
cipal, 30. 

Acid salts, 20, 44. 

Adhesion, 10. 

Air, 107; changes in, 109. 

Alabaster, 155. 

Alcohol, 195; alcohols, 195; methyl- 
ic, 195; amylic, 196. 

Aldehydes, 197. 

Alkaline, 42. 

Alums, 171. 

Aluminum, 170. 

Amine, 110; ammonia, 45, 110. 

Ammonium, 111; theory, 111; com- 
pounds, 113—4. 

Amygdalin, 207. 

Amyloses, 204. 

Anhydrides, 76; anhydrous, 75. 

Antimony, 129; antimonic acid, 132. 

Antiseptics, 190. 

Antozone, 90. 

Aqua fortis, 115; 7'egia, 62. 

Arragonite, 154. 

Arsenic, 125-6; acid, 128; tests, 127. 

Arsenous acid, 126 ; arside, 126. 

Ate, 17. 

Atom, 9 ; atomic theory, 9 ; weight, 
10, 49, 50-2. 

Atomicity, 23-4, 49; of salts, 29; 

variation in, 28-9, 32-3. 
■Azo, 192. 

Baking Soda, 80. 

Barium, 157. 

Bases, 42, 76, 88; organic, 213. 

Benzoic acid, 210. 

Beryl, 169. 

Beryllium, 169. 

Bi, Bin, 15, 20, 44. 

Binary compounds, 14. 



Bismuth, 133. 

Bivalent, 25, 

Blende, 166. 

Boettger's test, 133, 207. 

Bone ash, 120. 

Boracic acid, 105 ; boric acid, 105, 

Borax, 82. 

Borine, 214. 

Boron, 105. 

Brass, 166. 

Brimstone, 90. 

Bromic acid, &b. 

Bromine, 63. 

CESIUM, 83, 
Calamine, 166. 
Calcium, 153; group, 153. 
Carat, 134. 
Carbolic acid, 211. 
Carbon, 136 ; group, 53, 135, 
Carbonic acid, 140. 
Cassius' purple, 135. 
Caustic potash, 78 ; soda, 80. 
Celestine, 158. 
Cellulose, 206. 
Cerium, 185, 
Chalk, 154. 
Change of state, 9. 
Charcoal, animal, 137; wood, 137, 
Chemical aff,, 8 ; action, 37 ; change, 7. 
Chloric acid, 63. 
Chlorine, 57-9 ; group, 53, 57. 
Chrome yellow, 183. 
Chromic acid, 183. 
Chromium, 182. 
Cinnabar, 165. 
Citric acid, 210. 

Classification of elements, 56 ; organ- 
ic, 192. 
Clay, 170. 

Coal. 138: gas, 138. 
Cobalt, 43. 
I Cohesion, 10. 

223 



224 



INDEX. 



Collodion, 206. 
Copper, 160 ; group, 160. 
Copperas, 177. 
Corrosive sublimate, 164. 
Corundum, 170. 
Cream of tartar, 210. 
Crocus, 176. 
Cryolite, 67. 
Cyanic acid, 213. 
Cyanogen, 45, 147, 212. 
Cyanuric acid, 213. 

Davy's lamp, 145. 
Decay, 190. 
Decomposition, 8. 
Deliquesce, 167. 
Deut, 15.- 

Dextrin, 206^ dextrose, 205. 
Bi, 15 ; diatomic, 25. 
Dialysis, 149. 
Diamines, 214. 
Diamond, 136. 
Diatomic, 25 ; dibasic, 44. 
Dibromanthroquinone, 141. 
Didymium, 185. 
Diffusion, 107-8. 
Dithionic acid, 94. 
Dyad, 25. 
Dynamite, 200. 

Efflorescence, 81. 
Electrical attraction, 34; relations, 33. 
Electro, 34. 
Elements, 8. 
Emery, 170. 
Epsom salt, 168. 
Equivalent, 22-3. 
Erbium, 169. 
Essential oils, 203. 
Ether, 197. 

Ethers, 194; compound, 195-7; mixed, 
195. 

Fats and oils, 200. 
Fermentation, 190. 
Ferricyanides, 212. 
Ferrocyanides, 213. 
Flame, 143 ; tests, 146. 
Fluorescence, 87, 185; fluor spar, 

156. 
Fluorine, 67. 
Formic acid, 198. 
Formulge, 11, 49: empirical, 191; 

graphic, 31 ; rational, 191. 
Fractional distillation, 191. 
Fruit sugar, 205. 
Fulminic acid, 213. 
Fusel oil, 196. 



Gadinoltte, 169. 

Galena, 158. 

Gallic acid, 211. 

Gallium, 185. 

Gangue, 157. 

Gas, 10. 

Glass, 172 ; soluble, 82. 

Glauber's salt, 80. 

Glucinum, 157. 

Glucoses, 204-5 ; glucosides, 207. 

Glycerin, 200 ; glycols, 199. 

Glycolic acid, 199. 

Gold, 134. 

Graphite, 136. 

Groups, 8. 

Gum arable, 206. 

Gun-cotton, 206. 

Gun-metal, 166. 

Gypsum, 155. 

Hematite, 176. 
Hardness, 155. 
Heavy spar, 157. 
Hexad, 25. 
Homologous, 187. 
Humidity, relative, 109. 
Hydrates, 75. 
Hydriodic acid, 67. 
Hydrobromic acid, 65. 
Hydrocarbons, 193. 
Hydrochloric acid, 60. 
Hydrofluoric acid, 68. 
Hydrogen, 69. 
Hydroxyl, 45. 
Hyper, 18. 
Hypo, 18. 

Hypobromous acid, 65. 
Hypochlorous acid, 62. 
Hypophosphorous acid, 155. 
Hyposulphurous acid, 102. 

Ic, 19, 20, 29. 

Iceland spar, 154. 

Ide, 14. 

Indium, 185. 

Insolubility, 38. 

Introductory, 7. 

Iodine, 65. 

Iridium, 184. 

Iron, 173 ; iron group, 169. 

Isologous, 194. 

Isomerism, 188. 

Isomorphous, 172. 

Ite, 17. 

Kakodyl, 214. 
Kaolin, 172. 
Kelp, 65. 



INDEX. 



225 



King's yellow, 129. 
Kreasote, 211. 

Lac, 204 ; sulphuris, 91. 

Lactic acid, 199. 

La^vulose, 205. 

Lakes, 170. 

Lampblack, 136. 

Lanthanum, 185. 

Laughing gas, 118. 

Laws of chem. comb., 21 ; const, pro- 

por., 21 ; multiple propor., 22 ; 

volumes, 45-9. 
Lead, 158. 

Libavius' fuming liquor, 151. 
Lime, 153; chloride, 15; stone, 154. 
Liquids, 10. 
Liquors, 196. 
Litharge, 159. 
Lithium,' 82. 
Litmus, 42. 
Loadstone, 177. 
Lunar caustic, 84. 

Magnesia, 168; alba, 168. 

Magnesium, 114. 

Malachite, 162. 

Malic acid, 209. 

Manganese, 179. 

Mannite, 207. 

Marble, 154. 

Marsh gas, 194. 

Marsh's test, 129-30. 

Mass in reaction, 39. 

Massicot, 159. 

Mastich, 204. 

Mendelejeff 's law, 50-2. 

Mercury, 163. 

Metals, 8; metalloids, 8. 

Meta phosphoric acid, 103-4. 

Methane, 193-4; methene, 193; me- 
thyl, 193 ; methenyl, 193. 

Minium. 159. 

Molecule, 9; molecular weight, 13, 
23, 49. 

Molybdenum, 184. 

Mon, 1 5 ; monobasic, 44. 

Monad, 25; monivalent, 25; mon- 
atomic, 25. 

Monsel's salt, 178. 

Moore's test, 207. 

Mordant, 170. 

Muriatic acid, 60-1. 

Naphtha, 202. 
Naphthalene, 202. 
Nascent state, 37. 
Native, 160. 

19* 



Negative, 33. 

Nessler's test, 114. 

Neutral, 42. 

Nickel, 181. 

Nicotina, 215. 

Niobium, 151. 

Nitre, 78. 

Nitric acid, 115. 

Nitro, 192. 

Nitrogen, 105 ; group, 53, 105. 

Nitro-benzole, 202. 

Nitro-glycerin, 200. 

Oil, myrbane, 202; turpentine, 203; 
vitriol, 98, 102. 

Oils, fixed, 201 ; drying and non-dry- 
ing, 201. 

Oils, volatile or essential, 203. 

Olefiant gas, 199 ; olefins, 199. 

Oleic acid, 210. 

Oleoresins, 204. 

Organic analysis, 190-1 ; bodies, 186; 
chem., 186; bases, 215. 

Orpiment, 129. 

Orthophosphoric acid, 103. 

Osmium, 184. 

Ous, 19, 20, 29. 

Oxalic acid, 199. 

Oxidizing agent, 89. 

Oxybutyric, 199. 

Oxygen, 85 ; group, 85. 

Ozone, 89. 

Palladium, 153. 

Paraffins, 193. 

Paris green, 162; plaster of, 155. 

Penta, 2b', pentad, 25. 

Pentathionic acid, 94. 

Per, 18. 

Perchloric acid, 64. 

Permanganic acid, 180. 

Pewter, 159. 

Phenol, 211. 

Phosphates, 123. 

Phosphene, 122. 

Phosphoric acid, 123; phosphorous, 

123. 
Phosphorus, 120-1. 
Photography, 84. 
Physical change, 7 ; force, 37. 
Picric acid, 211. 
Pig iron, 173. 
Platinum, 152. 
Plumbago, 136-7. 
Poles, 33 ; positive, 33. 
Polymeric, 188. 
Porcelain and pottery, 172. 
Potassium, 77 ; group, 54, 68. 



226 



INDEX. 



Pressure standard, 47. 

ProtOy 15. 

Proximate anal., 188; princip., 188. 

Prussian blue, 179. 

Prussic acid, 212. 

Puce, 159. 

Puddling, 174. 

Putrefaction, 190. 

Pyrites, copper, 162; iron, 177. 

Pyrogallin, 211. 

Pyrophosphoric acid, 123-4. 

Quadri, 15. 
Quantivalence, 23-4. 
Quasi- elements, 44. 
Quevenne's iron, 173. 
Quintyl, 187. 

Kadicles, 44 ; series, 187. 

Rancidity, 201. 

Rational formulae, 191. 

Reactions, 35-41 ; reagent, 35. 

Realgar, 129. 

Red precipitate, 164. 

Red oil, 210. 

Reduction test, 187,- agent, 89. 

Reinsch's test, 127-30. 

Resins, 203. 

Respiration, 109. 

Rhodium, 184. 

Rochelle salt, 210. 

Rosin, 208. 

Rouge, 176. 

Rubidium, 83. 

Ruby, 170. 

Ruthenium, 153. 

Sal meatus, 78; ammoniac, 114; 

soda, 80. 
Salicylic acid, 210. 
Salt, common, 81; Epsom, 168; 

Schlippe's, 133. 
Salt of sorrel, 199. 
Saltpetre, 78. 
Salts, forms of, 44. 
Saponification, 201. 
Sapphire, 170. 
Saturated comps., 26-7; solutions, 

26-7. 
Scheele's green, 162. 
Scheelite, 152. 
Schweinfurth green, 162. 
Selenite, 155. 
Selenium, 103. 
Sesqui, 16. 

Silica, 148; silicon, 148. 
Silver, 83 ; German, 166. 
Slag, 173. 



Slaking, 154. 

Soaps, 201. 

Sodium, 80 ; amalgam, 113. 

Soils, 142. 

Solder, 159. 

Solids, 10. 

Solution, 72. 

Specific heat, 50. 

Spectroscope, 146. 

Speculum metal, 150. 

Spirit of salt, 60 ; wine, 195. 

Stalactite, 155 ; stalagmite, 155. 

Starch, 206; test, 66. 

Steel, 175. 

Stibine, 130. 

Stibium, 129. 

Strontianite, 158. 

Sub, 15. 

Sublimation test, 127. 

Substitution, 189. 

Succinic acid, 199. 

Sucrose, 204. 

Sugars, 205 ; tests for, 206. 

Sulphur, 90; bases, 92; salts, 92. 

Sulphuric acid, 98. 

Sulphurous acid, 96. 

Symbols, 11. 

Tannix, 208. 

Tantalum, 151. 

Tartar emetic, 131; salt of, 78; 

cream of, 210 ; soluble, 210. 
Tartaric acid, 209. 
Tellurium, 103. 
Temperature standard, 47. 
Ter, 15; tetra, 15: tetrabasic, 44; 

tetrad, 25 ; triamines, 214. 
Terpenes, 203. 
Tetrathionic acid, 94. 
Thallium, 135. 
Thiosulphuric acid, 102. 
Thorium, 169. 
Tin, 150; crystals, 151; plate, 151; 

stone, 150. 
Titanium, 151. 
Tri, 15. 
Triamines, 214; triad, 25; triatomic, 

2o ; tribasic, 44; trivalent, 25. 
Trithionic acid, 94. 
Trommer's test, 207. 
Tungsten, 151. 
Turnbull's blue, 179. 
Turpentine, 203. 
Turpeth mineral, 164. 
Type-metal, 159. 

Ultimate analysis, 190. 
Urn, 14. 



INDEX. 



227 



Univalent, 25. 
Unsaturated coinps., 27-8. 
Uranium, 184. 

Valency, 25-33. 

Valeric acid, 198. 

Vallet's mass, 177. 

Vanadium, 135. 

Venetian red, 176. 

Ventilation, 110. 

Vermilion, 165. 

Vinic acids, 195. 

Vitriol, blue, 162,- green, 177; oil of, 

98; white, 167. 
Volatile oils, 203; alkali, 111. 
Volatility, 39. 



Volume combination, 45-9. 
Vulcanizing, 204. 

Water, 71-5 ; of crystals, 75 ; nat- 
ural or mineral, 73. 
Witherite, 157. 
Wolfram, 152. 

Wood spirit, 195 ; fibre, 206. 
AVrought iron, 174. 

Yttrium, 169. 

Zinc, 166; group, 166; wMte, 167. 
Zircon, 152. 
Zirconium, 152. 



